Trying to down grade my package for the last 2mnts

I have been contacting Multi Choice call centre since July tk have my two packages down graded. I called a number of times and have caller ID's for the calls which I have logged but no success. Although the last agent I spoke to advised that I won't be billed when I check my balance due via USSD function I can see that I am being held liable regardless of my many attempts of calling before my payment date. What more do I need to do? Both my packages are still on premium and I cannot afford to pay it. Caller ID's: ***0-I25 and I31 respectively.