multichoice dstv

I have been a customer of multichoice for quite a few years. I recently discovered they have been overbilling me . charging me for a decoder that i dont use for more than 4 years. i only have 2 decoders (1 explorer and hd decoder) i am aware i have insurance on the 2 decoder and extra view. but found out to my shock that i was charged for 3 extra views and pvr . i dnt know how long this has been going on. i have the dstv whats app chat,wher i also was given different amounts that was owing on my account than i call than they promise they will debit the amount the suppose to but than they debit more than they should. I cancelled my subscription with dstv , i was told it was cancelled but when i phoned it wasnt the lady only than cancelled. ive laid numerous complaints with dstv -everytime they tell me it has been escalated ,but no one gets back to me i always phone to follow up.