MacBook Air screen fails

This will be the fourth year that I have my MacBook Air (1,8 GHz Intel Core i7 processor) and the screen fails increasingly. Sometimes when I turn on the Mac the screen came in black and white and I have to spend a lot of time trying to find the right position to turn in back to the the normal colours. But last week was even worst because sometimes the screen was totally in white and I couldn't see anything. So, I had to turn off the computer and turn on again... Is this normal? Is there a way to fix it or it's better to buy another laptop? Does Apple Store buy old laptops to fix?

Thank you.