Account incorrectly handed over to legal

In 2012 i had an ADT account at my house in Ormonde, therafter in May 2013 i renovated my house and notified ADT of the changes and asked them to suspend my account, i have since been struggling with ADT where they advise they never got any notification and kept charging me, i sent them proof of request and they have to date not acknowledged my request and now the account is with the lawyers and they send me me letters of demand, i now have another account with ADT dore a new contract as the old one i was advise that the matter was resolved and closed, how could ADT give me another account when i still owed the previous one, my credit record and scoring is being detrimented. Please assist with resolution. Tsholofelo Ndhlovu ***