Faulting us for their billing mistakes

We had a price lock agreement with MultiChoice in 2018, we struggled for multiple weeks to get it cancelled after the 12 period with them stating our notice is in one month and continued like that, we eventually got it cancelled end of 2018, beginning of 2019. Now in January 2022 we get a call from a debt collector and we are running a risk of getting a bad credit record. We have not had dstv for almost 2 years or heard anything from mulitichoice., We read up online and saw that they have issues with their billing system, and yet they still want to hand us over to a debt collector. This is ridiculous and unacceptable!!