Incredible Connection Cresta

On 9/3/18 I bought a Seagate 4TB hard drive from the Greenstone branch. They were out of stock and the one they had left in stock was used by someone else and returned so they marked it at 20% off. My hard drive crashed on 21/9/19 so I took it to the Cresta branch for some help with it, according to the guy at the tech desk, Oliver, my hard drive was dead and it would take approximately 10 days for a payout. Upon looking at my device, he noticed the sticker on the casing of the hard drive containing the serial number had fallen off, I pointed out to him that it had been sold to someone else previously and he claimed to understand, I provided him with the slip and the serial number on the box with all the other identifying markers and information. He claimed that it should be no big deal and the issue would be resolved promptly. I called the store 8 days later to find out what was going on, after 3 calls and a half an hour later, I finally managed to get through to Oliver who claimed that the supplier couldn't confirm that it was their product even though it had their branding on the casing of the device. I got extremely frustrated with him when he put the phone down on me and I decided to call their customer services, I spoke to a lady by the name of Sumaya who said she'd open up an investigation into the store and technician. I waited for 2 days to receive my reference number and after that I called the customer services again and spoke to a Mishka who claimed the call was not even logged. I then relived my frustration and told her the story and I got a reference number with a promise that a call would be made to me within 24 hours to resolve my issue, that was 2 days ago. I am extremely disappointed and frustrated with the service of this company. I can go as far as to say I hate them. I just want my credit for the faulty device and I will never buy anything from them again.