Discovery not so Healthy...?

So I became a "Private member" after being a corporate member of Discovery for around 15 years. I call the call centre to ask about how the billing works, as my account was suspended. Oh, they say, you have to pay in advance now. Not arrears anymore. I immediately transfer the funds and they reinstate my policy. Come January this year, I change to a lower / cheaper option and expect to pay the desired "new" premium. In advance. For January, right? WRONG!! They apparently bill me in arrears, and now I owe them for December....!! So I told them to blaas doppies, and take my business elsewhere..... THE STING: Despite NUMEROUS calls and emails to their call centre / helpline, NOBODY feeds back to me about the result of them reviewing the tape recordings of the integral conversation around this advance vs arrears payment.... Now they've got lawyers calling me for this "arrears" amount!!!! Who knows whereto from here??? HelloPeter, you are my last resort. HOPEFULLY somebody with a fair level of intelligence picks up on this and resolves this MASSIVE faut pas....