Your form field names have extra quotes in them...
name="“eCart1_1_Quantity<?php echo($row_WADAProd['ID']); ?>"
should be:
name="eCart1_1_Quantity<?php echo($row_WADAProd['ID']); ?>"
Then the corresponding binding should look like:
<?php echo($_POST['eCart1_1_Quantity'.$row_WADAProd['ID']]); ?>