I don't think there is anything to check because one may withdraw an application only in
the prescribed manner - and, AFAIK, making a phone call with such a request is not one of them. Also, an application once withdrawn cannot be un-withdrawn by a subsequent verbal request to do so.
You must appreciate that you are dealing with issues that have legal bindings ... not buying grocery where you may cancel an order whenever you like and re-instate a cancelled order subsequently!
Ask your employer to call the
employer helpline to enquire about your right to stay and work in the UK. The UKBA contact centre will not provide you the status (or any other information) about your application or what your phone calls have ultimately resulted in!