DSTV struggle to cancel

What a horrible experience. I've had DSTV for many years and decided to cancel due DSTV getting very expensive. After canceling in April they deducted from my account in May and June after which I had to get reversals, now all of a sudden I get phone calls from a debt collector stating I owe DSTV money.

Why is it such a struggle to get DSTV of my back???

My cancelation code is ENQUIRY REFERENCE NUMBER : ***4 stating my DSTV is cancelled since 01/05/2021.