FYI, if you are unlucky enough to be involved in a road traffic collision it is 100% upto you where your car is repaired, NOT your insurance company, although they will try they cannot force their choice on you.
Some insurers will try and strong-arm you into using their nominated bodyshop, some will even threaten to withhold their courtesy car or even double your excess, they're bandits like that, but it is still upto YOU who fettles it.
Most bodyshops will provide you with a courtesy car anyway, so that's a pointless argument from the insurance companies, however, if you specifically pay for a courtesy in your policy they cannot uphold this anyway and they have to provide you with a car no matter what.
To the OP, the odds are extremely high that your car has been repaired with spurious, non-genuine parts, but if you had of know what I've told you then you could have insisted on a main dealer bodyshop. They would have only used genuine parts and manufacturer approved repair methods, and also ensured that the anti-perforation warranty, (if applicable), is not jeopardised in anyway.
So remember folks, it's your car, and if you are involved in an accident, whether it's your fault or a third party fault, it is also your decision, and your right as to who repairs your car.