Mine was done by Rustbusters in Poole. They do a full classic car, white and black waxoyl. Expensive, but very good quality work. Cheaper by far than new wheel arches .
I had no underseal at all on mine as it was from the extreme south of Japan, so went for this one. After two and a half years it still looks immaculate. Worth it if you are planning to hang on to the Bongo.
Discount Trucks are brilliant though

and any work you have done there will be top notch.
The BewilderBeast - V6 Mean Green Tintop with LPG and 321 Away Montague Conversion