Poor customer service

I went to MTN store in Polokwane Mall of the North on the 02/01/25 to apply for a contract, I was told I owed R638.06 from the contract I cancelled in Aprill 2022 as I didn't want to upgrade(my phone was still in a very good condition, I didn't need a new 1) and I paid it. My application was approved, and I received the device on the 09/01/25. The next day I noticed some strange noise, that sounded like a loose part inside the phone(Huawei Pura 70 Pro).I then took it back to the store on the 11/01/25, hoping to get a replacement on the device instead it was booked in for repairs. At this time they had recharged me 30G once off promotional data and I had already bought a screen protector for the device from a Vodacom store that cost me R299.00 as per recommendation from the lady from Huawei, the screen protector was not available in the MTN store so I went to buy it next door as I wanted to keep my new phone safe. I was promised a new phone, I waited for it or feedback until became impatient and felt like my business and my need for the phone was not value. On the 22/01/25 I went to the store and I was told that they are awaiting approval from the manufacturer but promised I will get a new phone by Friday the 24/01/25. On Tuesday 28/01/25 I went to the store, and was forced to terminate the contract as I was still without a phone and they had sent me a bill and they seemed not to have a problem with it, they adviced I send a termination email which I did. Through all of these, they never bothered calling me for an update and/or appology for the inconvenience, I was the one calling and going to the store.

Now they are telling me they are going to charge me for what I have used versus what was recharged but they refuse to refund me for the screen protector I bought for the phone I don't have, and had intentions of keeping. I feel this is unfair to me.