how long already?
personally I never had my tints change colour like this. NEVER.
The only time I replace them is usually when they are too old and start to ripple.

means only less than 1 year, your gold already totally faded?
from the photos, your gold only remain a tiny bit on the edges of your windows!
Hard to comment because there are simply too many tint brands on the market.
I guess the one you installed just isnt too good.
The shop sounds unresponsible! Did they warn/inform you that the tint colour will fade after 6-8 months?

those sneaky bastards. the colour totally changed from gold to.... something else!
Since they say like this, if you really wanna claim, I suggest you use a heatgun and sparingly damage the tint in patches.
claim warranty. hahaha.... but make sure can claim before u do it. and also make it look like an accident (I mean, look natural)

Dont know how much u are charged for these tints.
But to me, colour fade/change after 3 months is unacceptable.
Must be very very poor quality dyed tint paper.

well u have 2 options now
1. complaint at consumer tribunal and force this shop to honour the warranty
2. learn from lesson, and blacklist this shop forever

I'm no expert, but from what I know tints have cheap type and good type. and then there are expensive type. cheap ones are usually just dyed films. the good type are metallic. finally those special ones are ceramic, if not mistaken. I usually use metallic as they seem to offer the best balance between sun protection and cost. I usually change my films about 7 years in average (from memory) due to ripples (uneven, not smooth anymore)