Useles!!!!!

I have been struggling for Cell c for 5 weeks now.So I originally bought a prepaid device back in February 2019 which was a LG Q Stylo 4 plus for R6000 a week later a dead pixel appeared on the display and I took it back as it was in it's 7 day returns policy.After that I was given a 12 month warranty on the device.So just before the 12 month warranty expired there was yet another display fault and I took it back to Cellc newmarket for repairs.3 weeks later they called me from the store to inform me my device was ready to collect and it was a manufacturer fault.To my demise it was a LG Q60 at half the price and specifications of the original device so I refused to take that device.So they sent the LG Q60 back to the repair center now 2 weeks later they want to give me a refund but the value of the phone has decreased to R3000 at most.I feel this is very unfair towards the consumer as I bought the device for a reason.There is a newer model of the phone but they can't exchange it to that or give me the original purchase amount that I bought it for.I spoke to a lady her name in Singele at Cellc head office and she referred me to ICASA.I need help I as the consumer can not take the loss becuase of poor after sales support and a manufacturer's fault