Over billing customers

It all started in December where my direct debit fell through and never transacted with a bill of R724, I then had a word with them and agreed to add it to the next bill however when the next bill came my bank then refused for them to deduct that money with the bill in January which was also at R724 however the R724 was January's bill was then paid, I then spoke to my bank and agreed to take their maximum amount that they can remove withdrawn, I then checked my withdrawals from them at the end of February which worked out to R1550 excluding my bill for February which was at R660, which clearly indicated that I was over billed, funny thing is that I actually confirmed with a team leader in the month of February which confirmed that my January bill has been paid,I've had numerous calls to the network all informing me about the same BS* all over again, not to mention the 12min hold times that I was placed on with every single call, I am absolutely livid with the customer service and the misinformation that they advise their customers. I'd like some form of conclusion with regards to my issue and compensation for the time that I wasted on their calls.