Bad/Unfair Customer Service

My iPhone X screen had a problem so I decided to take it to the Playground store in Melrose Arch to get it fixed. When I got there they requested R3800 to fix it. Comparing prices with other stores it was cheaper. They fixed my phone and it was working okay until the following month. I sent it back, they charged me another R1900. They said it was to repair the LCD. It went off again the following week after being replaced..I sent it back...it became a weekly thing. I got fed up and told them I want my money back. They refused and decided to transfer the problem to not been a screen problem but a mother board problem. I asked them why they didn’t tell me that it was a motherboard problem before they took my money and decided to do what they did. This was 2 weeks ago...I feel robbed and this was unfair customer service