Nextel, Sprint Sprint Afni collection cross referenced phone numbers and got my brother in law to try to collect a debt in my name Internet

I had service with Sprint where for 2 years i dropped calls non-stop, i  got 3 different phone at my expense that did not solve the problem, then i spoke to there help desk they could not solve the problem. The problem was they could NOT provide service in my area, so i told them i wanted to drop my service , they have been for 2 years trying to collect a disconnection fee, i spoke to Sprint many times to solve this issue they promised to take care of this issue, seeing how i paid my bills for two years on service that was total useless to me. The other day my Brother in law recieved a call fromAfni trying to collect this debt over the phone from him, on a bill i owed. Once we called the number he gave us that had contacted him, first they could give us no answers then they finallly explained they cross referenced the numbers and came up with my brother in laws number, this is total BS and sounds very illegal let alone Harassment  why do these people get away with this crap......My phone is listed on a DO NOT CALL LIST  and bill collectors are not allowed to call and harass people for money... I want something done about this or i will seek legal action this is plain and very serious issue and i am very unhappy and don't feel this is a acceptable behavior for Sprint or Afni Collection ..  Thank you  Baltimore, MD.