Fixing the problem

I was checking my credit score the other day cause i was looking to buy a car and i saw that i have one account in defualt and it was a vodacom account which i had open 4 years ago. I saw that i owned R24 and had alot of missed payments and i was very angry. I call vodacom and they gave me vodacom legas details. I called and they asked my details to see if i still owed and what they found is that i dont owe a cent... I asked them to send me a proof of payment and to clear my name and they asked my email and im still waiting... Now im sitting with a default on my credit which is not my fault and those who cause the problem is just not fixing anything.