Cell C - exploiting pensioners

I have been struggling for months with Cell C who deducts money from my 80 year old father's account. He had a 3G stick on contract which we canceled. They then phoned him for another contract which he declined. The deduct money every week which we reverse. They claim my dad agreed to the new contract but we're still waiting for the recording. The initial contract was R99 and the new one R89 (which we never agreed to), yet they deduct R254 and R153 at a time and yesterday it was R700. Why would a 80 year old pensioner who is bed ridden want to renew a wi fi connection? He never uses it and they should be able to see that. This is pure exploitation.