I upgraded one contract in December with a premium of R542

I upgraded one contract in December with a premium of R542.08 vat excl.but an amount greater than R2341.73 excl vat on top of the expected installment was debited in February and March unaware and without my consent. When I asked, they said the data was not set to R1 limit as they did in my other contract I have with them but it was set unlimited. The consultant did not explain this to me when I took the contract. Please help I want my money back.