Debit order fees

I have a contract with Telkom and only took a router and data contract for R99 pm and to my surprise they deducted R402.98 which I was not informed about . I tried to call several times and asked for the matter to be escalated but unfortunately no response since the around end of October. We have other contracts with other companies but they never charge such ridiculous amount . With my situationist did indicate that I was in a process at work changing bank account which I was did not know which bank they will deposit my salary the next month. I made sure that there was money deposit in case of 2nd attempt before month end but they didn’t and just invoiced the debit order fees. We are not given any option on how to pay the money when the contract is initiated as debit order is the only option and we are charged when we have a crisis. This is totally unacceptable. Being a new customer with less than 3 months I’m disappointed and would like to cancel my contract.