Another Telkom problem.

I took out a contract with Telkom in 2018, an iPhone 7 Plus on a FreeMe 1GB to be exact. Two years later I cancelled my contract as I thought the agreed term of 24 months was finished. A few months go by and everything seems to be fine. I then receive notification from Telkom that I owe them over R5000 and that amount has grown now to over R10000. I went back to the store where I took out my contract only to find out that the data portion of my contract was for 24 months but the device was set for 36 months. I asked for a copy of my contract which they could not provide. I have logged numerous disputes and no one seems to be able to assist me. Can anyone please assist me with getting this resolved?