MTN debt collectors are calling everyday regarding the ***** cellphones contracts that was resolved by MTN as *****

I reported cellphones contract as *****. I then forwarded all the documents to them, and the matter was indeed resolved as ********** by MTN, but to my surprise I have different call s from different companies saying that I owe MTN. This is sad because the matter was indeed resolved as *****. MTN please tell your debt collectors to stop calling me.