Mondo

Mondo is having a bad service last year I took a phone from mondo it want June on the beginning of the month due to the closing of my work i send it back from mtn on the 15th of June. The thing now is that since I send the phone back from mtn my name has been blacklisted they never make the cancelation for me for that phone that I've send back to the I phone mondo they send me to mtn when I go to mtn they said mondo should be the one who is removing my name from the blacklist them they can't help me they are the franchise I've been keeping phoning mondo emailing them until now they can't give me the right answer until now.so me I'm blacklisted for the phone that I send to them back I can't get anything because of this mondo so no I need help about this