frustrated with dell support

I bought the new g3 gaming from dell and paid almost 800 for it hoping that with that price tag I would get a good device. however, the laptop came slow and it took almost 10 minutes to start. At the 30 day mark, I was going to return it but had good faith in dell because my family has been buying from them for so long. that was my first mistake. the guy took control of my laptop and did some things and told me the laptop should be working fine and I believed him. that was my second mistake, a couple weeks later the laptop was slow again and so I contacted the same guy and he told me to send it in. I believed that would fix the issue because I had to send it in and they were going to do something. they instead replaced my hard drive and that didn't change the speed or anything about the laptop. my laptop also came back with new scratches a black mark I can't rub off. I contacted the returns team which sent me to the replacement team which sent me back to technical support. I understand the thirty-day policy and I would be fine taking in-store credit cause I need a laptop that works. no one seems to be able to help me so this is my final shot.