Poor service

I am upgrading my contract but could not proceed as apparently have arrears of R122 on an account that was cancelled months ago. First i hear of this so i phoned telkom to ask as its debit order and should not owe anything. Either way i said i will pay it but need the account nr that was cancelled as reference for eft - they could not give me the account nr as not on their system - this is extremely frustrating. No assistance at all