Vodacom

I had a prepaid cellphone contract with Vodacom , in 2015 the contract expired and I upgraded to an iPad air, The iPad that I received was NOT PREPAID contract. I got it in February 2015, I received a bill from Vodacom that I owe them R9000 for data usage. They blocked my account and stoped debiting money from my account. The account was then handed over to some lawyers . I still didn't pay as I did not sign for their contact . Their bill is affecting my credit record till date. I got hold of the lawyers so that they can tell me how much I owe so that I can start with payments. They told me that they are not the ones who are handling the account. I called Vodacom SA and explained my story. They couldn't trace that account, I even visited their branches several times and still no help. How ,where do I pay? Do I really have to pay them? The amount that reflects on my credit record is R26 000. I understand that I must pay for the IPad BUT not the R9000 Data usage that I did not sign for. They were not transparent