Exploitation, Bad service & Passing the buck

In 2017 CellC offered my father, 78 year old pensioner, a 2 yr cellphobe contract & 2 Citrus Jazz phones were delivered to him. The monthly payment was R180 pm for both phones. After a few months, one of the phones was faulty and upon making enquiries CellC informed my dad they will not be able to fix the phone as they do not have parts for the phone. My dad then decided to call the contracts & he had an amount of R741 cancellation fee per cellphone where after he faxed proof of payment in the amount of R1,482. CellC confirmed proof of payment & they told my dad that he's account has been settled & that he does not owe CellC any money. However, after a few days later they deducted an amount of R180 as well as a R90 from my dad's bank acc. My dad made several phone calls to CellC and every time he must explain the situation to a different call centre agents. They've been sending him from Pontius to Pilate on so many occasions & I do not think that it's fair that they treat him in such a manner. He also had to send proof of payment thrice because they could never find any of the emails regarding proof of payment. This last straw is that CellC is now threatening my dad with legal action for an amount of a lousy R108. 09.....this is totally preposterous. I'm so disgusted with their service towards my dad.