Can MTN really debit you whatever they feel like?

I upgraded my phone in May and renewed my contract. Over the phone, I was quoted a monthly subscription fee of R550. Ever since the upgrade I've been debited R690 every month. <br> <br> I tried to call the call centre, but eventually gave up after never getting through.<br> <br> I emailed the customer care centre twice (queries ***2 and ***5). The result? I was informed that there was an increase in April. But then why was I quoted R550 in May??<br> <br> I also logged a complaint on the MTN website (complaint ***). I've now had two call centre consultants email me back and refer me to my statement link.<br> <br> I DON'T WANT TO SEE MY STATEMENTS. I've already seen them. I want a supervisor to explain to me why I'm being charged more every month with a valid explanation! I've explained this in the emails.<br> <br> Even if there was a misunderstanding, I'd like them to check the telephone recordings. I'm sure I wouldn't have written down the amount for fun.