No response to email and paying more than I signed up for

I while back I upgraded my contract and got charged double + more, I spoke to a consultant that said there was a problem with the migration of the contracts and that I have been invoiced for both. She also said that my account will be credited with R346.96, but It's been 1 month and nothing has happened. And the full R1131.01 has been debited from my account anyway without any credit. And no one rep**** to the mail that I sent with the confirmation email of the contract + price that I should be paying for. Next month is upon us and im still going to pay more than i bargained for.