Review Disappointing CENTRAFFIN contract

I signed up with Centraffin over 3 years ago when I ran a medical practice in the Western Cape. My practice closed due to unforeseen circumstances and I relocated to a Pretoria. I tried to cancel the monthly debit order with centraffin for over a year unsuccessfully and now have opened a new practice in Gauteng. Centraffin provides phone sets for national telecoms I believe and I am unable to contact anyone who can help me utilize what I am paying for.I tried to return the phone sets to them . Every month over a thousand rand is debited from my account for no service and have been told that the contract is a contract and that I would need to pay a huge amount of money to cancel . Surely this cannot go on.