********** charges and it's my problem?

I was a loyal customer for over a decade, but had to cancel last year as o changed medical aid schemes and couldn't afford the full rate. I cancelled in November, was told that I had to pay into the end of January as it's a full "calendar month". Ok fine, let that happen. I ended up back on vitality in Feb and decided to join Virgin, and the contract attached to the cancelled planet fitness, I waited it out, out connected the Virgin contact in March, no issues so I KNOW it was cancelled. February they debit my account, I reverse it, March, April, May, debit debit debit, reverse, reverse, reverse. I got a call in June to ask me to pay those erroneous charges, I explained the contract was cancelled, no more debits.

Now apparently I have been handed over for debt collection and am being harassed for something that shouldn't exist? What on earth must I do to be free of this company???(the answer seems to be pay for no services rendered or they harass you to death?).