Unacceptable Client Service

How do you hand over a client for a contract that was cancelled in 2012 or 2013 and done so in your Bayside Branch personally. There has been NO communication and no report that there is a problem. After upgrading one of my other contracts in December that was an eppic fail and took months to sort out by a senior manager still nothing was ever communicated that there was an outstanding amount. The company Select Online cant give me any information as to why my account has been handed over just the amount. Cell C's legal department cant give me any information because the account has been handed over. So how does this problem get resolved.