Charged incorrectly for internet.

I requested to downgrade my internet speed after Axxess upgraded it twice without my consent. They sent an email saying it had been downgraded with an amended invoice and yet, I was still charged incorrectly for my internet. My bank account was charged twice. When I phoned Axxess the lady who answered was so rude and unhelpful I am seriously considering switching my ISP altogether. Axxess staff are always rude on the phone. They refuse to credit me correctly for all the overpayments made.