unfair blacklisting

My huand has been having this issue with mtn since last year, now its been handed over and he is blacklisted and it affects both of us.. He cancelled conrtract last uyear 2014 and the and future deactivation of phone was set for 15th June the consultant even printed us e-mail reply from headoffice, 2015 June my husband finds out MTN blaclisted him and apperently there's a fee he has to pay AGAIN for this contract to be closed pkease assist becaase thes is really upsetting. Or must we now involve the lawyers