MTN stole my number.

I have had my MTN cell number for close to 19 years. The other day, when I tried making a call, it told me that my line has been suspended, which I could not understand because I've been on a pay as you go for over a year now. When I called MTN to see what was happening, they told me that my number has been linked to a data contract taken out by someone else who has not paid their bill, and that they cannot give me any details because I am not the account holder. How can MTN assign a RICA'd number to someone else's contract without written permission from the owner of the number? Also they have been most unhelpful in trying to resolve the matter. They are trying to completely avoid all responsibility in this matter. To date, nothing has been done, and my number is still linked to someone else's profile.