Which is the best trim restorer ?


My mini has the oe mudflaps which are showing signs of fading on the plastic (I am very disappointed !) I tried a specialist plastic restorer product but after a few days the fading re-appears.
Black wow(who in the UK supplies this?) is a product I have heard a lot about on various forums. Is this the best product to buy? as I don't want to waste time and money on other stuff that does not do the job (my back to black spraying days are long gone!)

All advice appreciated, Ag.