Cushion colour

[Zing]

I have sunbrella cockpit cushions, which I am pleased with mainly. Comfortable and non sweaty to sit on and quick to dry, but they look a mess. The colour is a lightish grey with blue piping. The problem is it shows some stains, marks and discolouration, which is uneven and I can’t clean them. They have been dry-cleaned, washed multiple times any which way you can think of, even bleached. They still look grubby, even though they are surgically clean. I think a navy blue might look smart for longer, but would be horribly hot in the sun.

Any suggestions for replacement material, patterns or colour?