If you haven't already done so, ask to escalate your complaint and that you now require a case manager to resolve your problem.
I had issues with BT, serious ones of which they owed me a heap of money and were below any form of competence.
My case manager was sympathetic, helpful, understanding and dealt with my issue step by step.
I received all monies owed, received a wealth of free packages as well as some new phones.
A case manager WILL help you the best way forward and treat you like a human. That's my experience, not saying everyone has the same result but worth a bash.