Populate TextBox on jQuery AutoComplete DropDown (ComboBox) selection in ASP.Net MVC

I have 3 texboxes ( Name, Age, Address) and 1 checkbox (for email selection).

Name is dropdown while Age and Address is normal textbox.

On the dropdown change I want do:

when i choose Name it will autoload data for textbox Age and Address.

I already can do the combobox but for the auto load data in other textboxes is failed.  

This is my code 

 View

@using (Html.BeginForm("Save", "Home", FormMethod.Post))
{
    @Html.AntiForgeryToken()
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })

    <div class="form-inline">
        <div class="form-group">
            <label for="st" class="mr-sm-2">Platform:</label>
            <input type="text" id="txtPlatform" name="CustomerName"  onchange="get_sbu()"/>
            <input type="hidden" id="hfCustomer" name="CustomerId" />
        </div>

        <div class="form-group">
            <label for="st" class="mr-sm-2">PH Number:</label>
            @Html.TextBoxFor(m => m.pNum, new { id = "task" })
        </div>
        <label for="st" class="mr-sm-2">Base Type:</label>
        @Html.TextBoxFor(m => m.bType, new { id = "task2" })


        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-primary" />
            </div>
        </div>
    </div>

   
}

Script for autocomplete

    <script type="text/javascript">
        $(function () {
            $("#txtPlatform").autocomplete({
                source: function (request, response) {
                    $.ajax({
                        url: '/Home/AutoComplete/',
                        data: "{ 'prefix': '" + request.term + "'}",
                        dataType: "json",
                        type: "POST",
                        contentType: "application/json; charset=utf-8",
                        success: function (data) {
                            response($.map(data, function (item) {
                                return item;
                            }))
                        },
                        error: function (response) {
                            alert(response.responseText);
                        },
                        failure: function (response) {
                            alert(response.responseText);
                        }
                    });
                },
                select: function (e, i) {
                    $("#hfCustomer").val(i.item.val);
                },
                minLength: 0
            }).focus(function () {
                $(this).autocomplete("search");
            });
        });
    </script>

 Script for auto load data into textbox

<script type="text/javascript">
        function get_sbu() {
            var id = $('#txtPlatform').find(":selected").attr('value');
            $.ajax({
                type: "POST",
                url:"@Url.Action("GetData", "Home")",
                dataType: "json",
                data: "id=" + id,
                success: function (data) {
                    if (data.length > 0) {
                        $('#task').val(data[0].pNum);
                        $('#task2').val(data[0].bType);
                    }
                }
            });
        }
    </script>

 Controller

        //GET
        public ActionResult ViewList()
        {
            List<SelectListItem> items = new List<SelectListItem>();
            var selectItems = db.tblPlatformLists.ToList();

            foreach (var item in selectItems)
            {
                items.Add(new SelectListItem
                {
                    Text = item.list_id.ToString(),
                    Value = item.pName

                });


            }
             TempData["platform"] = items;
            ViewBag.platform = db.tblPlatformLists.Where(z=> z.iSelected == true).ToList();

            PlatformList PlatformList = new PlatformList();
            PlatformList.listPlatform = db.tblPlatformLists.Where(x => x.iSelected == true).ToList();
            ViewBag.platformlist = PlatformList.listPlatform;
            return View(PlatformList);
           
        }

        [HttpPost]
        public JsonResult AutoComplete(string prefix)
        {           
            var platforms = (from platform in db.tblPlatformLists
                             where platform.pName.StartsWith(prefix)
                             select new
                             {
                                 label = platform.pName,
                                 val = platform.list_id
                             }).ToList();

            return Json(platforms);
        }

      
        ///AUTOLOAD INTO TEXTBOX
        public JsonResult GetData(int id)
        {
            List<PlatformList> plist = populatePlatform();
            return Json(plist.Where(p => p.list_id == id));
           
        }

        private static List<PlatformList> populatePlatform()
        {

            order_15GEntities db = new order_15GEntities();
            List<PlatformList> list = new List<PlatformList>();
            var platform = db.tblPlatformLists.ToList();

            foreach (var item in platform)
            {
                list.Add(new PlatformList
                {
                    list_id = item.list_id,
                    pName = item.pName,
                    pNum = item.pNum,
                    bType = item.bType
                });
            }
            return list;
        }