If the paint doesn't match, then you should take the car back,
They are paid to return the car to the original condition.
If they squabble about it, tell them you will contact the insurance company who paid them.
IF they don't do anything, CONTACT that insurance company.
If they refuse to fix it still, take your can to somebody who will fix it and then invoice the insurance company. This happens more than you would think.
PM me for details of somebody who will do it required.
As for the driving of the car, do what your Mum always does, write a letter.
Nothing has ever happened ever in the world without paper work to support it.
Words are just words and cannot be proven.
If nothing happens, then go to one of those websites that publish shoddy workmanship, put them up there, and tell them you will forward the sire to everyone you know until they fix it properly.
I F*UCKING HATE BAD WORKMANSHIP
BASS OUT