She's had a reply from the garage:
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The rear tyres are fine at 3mm, the slight cracking isn’t an issue, I wouldn’t be recommending these to be replaced based on that alone.
The OSF tyre is at 5mm according to the video so that’s also fine. The NSF tyre appears to have some damage to the tread and although its mainly cosmetic, I can see why they have recommended that tyre. So you need 1 NSF tyre and the wheel arch liners refitting/replacing. - The video shows chunks missing fro the tyre at both edges (inner/outer).
I’ve looked at the history on the car and can’t see any reason for the wheel arch liners to have been touched. They are not serviceable items so I cant see any reason other than a manufacturing fault for them to be in this condition.
I take it your car is still with the retailer, if so, ask them to submit a goodwill case to JLR. I am happy for them to contact me direct for any support with getting your car sorted. - He knows where the car is, but wants my daughter to contact them and tell them to submit a goodwill gesture.
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So, basically, they will replace one tyre and the arch liners, but that means the other 3 tyres are cracked and worn, and the front will have a new tyre and another with ~5mm tread. Thus, causing uneven wear on the new tyre. He mentioned they will put the issues right as a gesture of goodwill, yet there is an admittance of a manufacturer's fault. I am baffled. Surely, they should be putting it right, and as a gesture of goodwill and apology, they should be replacing the other front tyre and possibly the rear tyre. Especially as one of the rear liners is damaged and has been rubbing on the tyre's inner wall.