Cannot edit data to show information on particular drop down selection

Cannot edit data to show information on particular drop down selection

Hello all wanted guidance with my code and a functionality shared part of code here.I want to show "Diesel variant not available)when diesel is selected for a petrol variant like maruti(brand),model(alto),fuel(diesel),b ut on changing the data "Estimation requires inspection of your vehicle. Please go ahead and book" it still shows the same sentence what can be possible cause and how to fix same.
function(data){
              if(data)
              {
                  if(data == 'No 0Price')
                  {
                      $('#amount').html('Please select all the filters');
                  }
                  else if(data == 0.00)
                  {
                     
                      $('#amount').html('Diesel variant not available');

                  }
                  else
                  {
                      $('#amount').html('<i class="fa fa-rupee"></i> ' + data);
                  }
                  $('#book_btn').removeAttr('disabled')
              }
              else
              {
                  $('#amount').html('');
                  $('#book_btn').attr('disabled','disabled');
//                  $.notify('Sorry! Currently we do not Provide service for this model');
              }

           }

.T hanks