Holding clients liable for a contract they know nothing about is not legal

I'm on a "pay as you go" agreement with dstv. Under this agreement I paid monthly and recieved service for that month. Last year we moved house and didn't make the monthly payment for obvious reasons. However, dstv took the liberty of continuing service. Months later, I started getting calls demanding an outstanding amount, for which I knew nothing about. When I phone the call centre 5 weeks ago, the agent advised that I had agreed to terms and conditions (again which I knew nothing about). Apparently, these conditions stated that dstv could provide me with service, for as long as they deemed and I would be liable to fit the bill regardless. The last time I checked I didn't sign a contract term, for this very reason. According to their policy I need to call in and cancel my service in the midst of a house move, despite the fact that there is no agreement in place.

She advised that she'd go back and listen to the recording where I had agreed to these T&C's and get back to me (which she didn't do). Three weeks ago I followed up and spoke to a manager who agreed to reduce the amount. He said would call me the next day, which he didn't do. Last week I called in again and spoke to another manager who said he would have to contact the agent and manger I had previously spoken to. Guess what I'm doing.... still waiting!