Since you have a vintage bag, is it true that the chain and the turn lock key is 24k plated gold? Do they replace it with non 24k plated gold? I guess I will see in 2-3 months..
Chanel has stopped manufacturing hardwares with gold plated many years ago...if they are replacing the chain and turn lock hardwares, most likely will use the current metal material... Why dont you call and ask to speak to the leather specialist (not the SA who took your order)?
There is another useful thread you can look up for feedback on the refurbishment on the hardware...