Charging wrong amount

I took two contracts in December at telkom westwood, one was for R399 and one was for R299, they didnt send me an invoice and when they debited they debited R399*2 = R797, it was telkom westwood and when i call them they are not picking up and there is no response to my email, lady name was Sinenhlanhla. When i log into my account the two amounts they are charging is R399 which is not supposed to be the case i want this to be resolved.