Incorrect billing - no response to queries

On the 30th of May my account was incorrectly billed (double the usual amount simply debited from my bank account) and I have still not had any response or resolution. The incorrect usage was during the strike action.<br> <br> I have tried to call to solve this problem but the call centre agents either hang up or are extremely rude. Every time I call they change settings on my account, for example, my usage limit is reset to zero without my permission. They NEVER resolve the problem.<br> <br> I want my account credited and changed to Pay As You Go.