Unable to resolve any of the many issues

I have a almost two year contract this May. From day one I had problems. Faulty handset that they didn't want to replace as I phoned the customer care for 2 weeks and time had laps for replacement. Never did I receive a reference number is it always \Just use your ID number "Trying to change the debit order date which never happened. More than one payment in one month ( bank statements as proof )"