3 months sounds a little excessive as I've been told mine should take 1 month and its an e class coupe so same number of doors etc to repaint as yours.
Seeing as you've had the car for over a year, realistically don't think much will be done regarding compensation/refund but you're welcome to try the dealership or customer services. Whilst the car is being repainted you should be given a courtesy car to minimise inconvenience...
Mine was 3 months from the dealer collecting the car to me getting it back.