Handed over account

I had a Vodacom account a few years ago, I thought the contract was paid off and i did not renew. I recently went to apply for credit and i was told that i had an outstanding Vodacom account that had been handed over. Naturally i went to Vodacom to enquire but they told me that they cant find anything on their system and i should bring the mobile number that i dont even remember. this is not fair to me because if i owe them I will pay them but they cant even tell me who they handed it over to and how to pay it if i do. All I want is to clear my name so I can be able to buy my house. Vodacom please find out if i owe you and if I do tell me how much so i can pay you and move on with my life.