all i can is JOIN THE GANG!
i have rust and the rover warrenty is a bloody fast. My car is always serviced and checked, and the corrosion warrenty was always done, so how comes its rusted? Well that aside, it has taken me 2 years of constant debating with rover, and i still didnt get anywhere.
I have had my arch done now, one new arch and what a job! A new arch cut a placed in and the shaping is perfect. Dont let people say 'putting a new arch on and welding will crack with the shutting of the doors over time' it may well be, please dont get me wrong but if its done properly it should be fine. Just make sure that the gargae is well credited, a member of some sort of automobile (not sure what it is, blue writing and a blue car with lines coming out and around it) as the brooklands green is not that hard to match, you should be fine. If the garage dosent do it then, give it 2 weeks and spray the arch with wax oil. Although 2-pack drys very quickly in comparison to celluoise (sp?) based it cant do it any harm.
Now, for some reason, the people that sell the replacment arches have been slow in getting them to the repair shops. The 200 chasis is considered quite old now (please no one take offence!) and the replacement arch is still not around. It may of just come out by now (fingers crossed) if not, the spray shop will cut, shape and weld a new arch from steel sheet. They should galvensie the panel.
I HTH and you get it sorted. It may be worth leaving it a little longer until it does get worse, either way, its best to cut it out, a little harsh but its considered a type of cancer for cars.