Not impressed with LG C5 77

Hi all

Had my LG C5 77 for 10 days after my C2 65. C2 was outstanding - clear, sharp, vivid. I've tried Netflix, BBC, ITV, Prime, 4k, UHD.... I just cannot see the same clarity in the 77. Grainy, dull.... just not impressed.

I've tried the same settings from my C2 and it is just not good.

I have 2 questions given that this C5 was £2000.

1. Anything I am missing settings wise?
2. If I exchange it, I don't want to expand the budget. Anything you would recommend?