MWeb decoder impossible to cancel this contract

For the last two years - on and off- I have tried to cancel my mweb decoder contract as we upgraded to DSTV explora. I have phoned a couple of times given mu details EVENTUALLy I got correct email address and emailed them all the details for cancellation - I eventually got an email back asking for all my details and account number but I had already sent that ! tanyway I filled in their form as requested emailed and see I am still getting charged only to discover their server kicks the cancellation form out as spam !! and I am still getting debited ?? for sometjong not used fpr two years??