MWEB IN ****!!! ?

I last had internet service May 19, 2018 after we moved addresses temporarily. Mweb did not manage to provide continued service at the new address because there was no supporting infrastructure. However, I was billed via debit order with no usage/service until I requested cancellation and Mweb collected the device. This was a month to month contract. To my surprise, over 3 years on, I just got a call from a lady *** informing me MWeb handed my account over to them for collection and I should advise about settlement within 3dys. The lady confirmed my ID number and requested my email address. When I did not see any email I called the number and a male answered, asked for my ID number again and said they have nothing in my name and has no idea who would have called me. Who are these people that MWEB is working with? If this is a ****, where did they get my Mweb account details? Why would Mweb wait 3years to follow up with a client? We do not know who to trust with our information now. This is crazy!