Pressed plates, or go to Halfords and get them to make you some new ones
get the lipped plate then cut the lip off - easy
^^^lolWhite one for the front of the car and a yellow one for the rear, both conforming to the UK road law...
Not quite sure that the lip would be easy to cut off as its made from the same material as the plate itself.
Anyway I've no need to go to that trouble as I collected a set of new plain plates from the dealers on Thursday complete with the sticky pads to stick them to the car. As we were in my A3 and not my wife's new A1 I said I was quite happy to fix them myself.
I've got 3D carbon letters and completely plain background had these about 8 years now and no hassel from plod