Macbook 15 2023 M2 Issues

I brought my NEW Mac Air 15 M2 Chip under a year ago. I started noticing horizontal lines that would affect the middle of the screen and the whole screen, however it isn’t permanent as it happens once a month roughly. I went into Apple Store on Brompton road and they said it would be fixed as uta under warranty. Unfortunately I got a quote back for £490 to fix it even though it is under warranty and I hadn’t damaged it.

After I got my MacBook and went home, I have now noticed that there is an anccount on my computer named “ul” which isn’t my account nor authorised. It has a password linked to the account and now I can’t login. This is a major safety concern. I spoke to Katie at Apple Brompton Road and she told me that that’s impossible….

I tried 10 times calling the shop and had no answer!