Galaxy Note 9 decolonisation issue

I'm using my Samsung Galaxy Note 9 more then year now. But within that year my screen got tinted phone was hard to use with horizontal lines. When I asked shop keeper refused fix it by telling it's a hardware issue and may cost more 30,000 LKR. So I couldn't able to further do anything. But everytime when I use my phone I feel then pain I invested in my phone, where 5 years old  my Galaxy Note 4 still have crispy and vibrant display. Just wanted to know any others also having this issue and how the overcome it?