Account Paid up

I had a contract with Vodacom which I took two cell phones with them, however my phones got ****** and they were not insured. I decided to call Vodacom to ask them to give me cancellation amount for my contract, I was referred to their accounts department and they gave me the amount. I paid that amount immediately as promised to the account department. after some few months I got a call from their call centre consultant demanding I should pay for my phones, when I tried to explain the two ladies didn't want listen to me. This year I have been receiving call from some lawyers saying my account has been handed over. I explained to them and responded with e-mail to them with full story however no one attended to it. I decided to check with ITC how much they say am owing them, I got the amount and pay the amount. what then am I still owing, actually I feel I shouldn't have paid the last payment as I already did. please clear my name and leave me alone. I have paid you your money.