cancellation of debit order

My debit order date is 20th of each month. In September my debit order dis not go through on this date so I phoned and was advised that there was a problem with standard.bank and fnb debit orders. I asked when will my account be debited and was given 30 sep. On 25 Sept my acc was debited with 648. On 30 sep another 648 went through. Yet again I ph and told them I will return the 1 debit order. A few days later I get automated voice messages saying my acc is in arrears. I phoned again and was advised that this is because mu debit order was returned. After complaining that this whole mess was vodacoms fault I was advised that the fee will be reversed. On 20th Oct. My acc was not debited I waited and was informed that my debit order was cancelled due to the debit being returned. You have really inconvenienced. me. I want a letter advising how much it will cost to cancel my contract as I have had enough of your bad service. Your call centre does not even know who to email for complaints.