Very unhappy i smart customer

In September of this year I took a cell phone contract with i smart, the monthly debit amount should be R349.00 per month, R115.00 airtime and 100 sms's. At the end of September I had difficulty, and the monthly debit did not go off my bank account. I phoned i smart and made arrangement to debit my bank account with the normal R349.00 and then R174.50, so that I can settle the outstanding amount from September that did not go off my bank account. On the 24.10.2018 the two debits went off my account like it should have. Only to be debited again on the 25.10.2018. I phoned i smart on the 26.10.2018 to inform them that the debit went off again, they instructed me to go to the bank and return the debit as it was a system error. I went and sent it back, and was charged R65.00 by the bank for sending the debit back. On Monday 29.10.2018 the debit went off my bank account again for the R523.50. I had to phone i smart again, and was instructed to go to the bank and send it back, I did and it cost me another R65.00. Today I woke up only to discover that another debit of R523.50 was debited from my bank account, I phoned them again this morning informing them of the double debit. Only for them to say sorry it is a system error. How long is this going to carry on for.

Who is going to refund me my R130.00 on charges for sending it back. They are not worried that my name gets flagged for sending back the debits. They are putting me in a very difficult situation as I have other responsibilities that needs to be payed. I am very unhappy about the service from i smart and want to cancel my contract immediately.