[Pasted from other thread]
Im doing the same. Both sides are rusty - one is bad.. but, only surface rust.. Im having both cut out and redone - best way. One side of mine has been done before.. but, it was a pretty poor job.. so bad, its come back worse than Ive ever seen before, hehe.
Im getting mine done at a place where Mat Brown has his stuff done (and local to me).. As for price, its going to be a bit more than normal as Im having it sprayed right down the A-Pillar too, to avoid any blow-in lines.. I guess you just have to find somewhere who you can see their work, and ask them to quote! Id imagine itd be about the £300 mark tho, to have it done similar to mine! (Excluding new Stickers, tho).
Remember, you will have to get two new stickers too if you have it done properly.. which are £26+vat each or something - I see so many people who mask round the stickers and its obvious its been sprayed then!
Let me know how you get on - mines going in on the 17th.. so Ill get some before and after photos - altho, photos are pretty bad at showing paintwork.
But yea.. get them both cut out, new arch put in and sprayed/sealed. Only way to stop it for sure.. ok, curing surface rust is fine.. but, if the sealent underneath is bad.. itll just rust again as soon as some water gets in!