Nigerian number plate fades over time.This could be as a result of the environmental factors or the standard of the materials been used.Also the vehicle owners uses strong detergent to wash their cars which can easily reduce the quality of the painting on the car and also the number plate.
Personally i have seen somany number plates been repainted.Unfortunately some are poorly done by road side artist.
All you need do is to pay for replacement(new one) and the problem is solve.
The challenge is that often times the quality of the new number plate may not be as thick as the old one but its genuine