Some great points flc, thanks.
My woes were with Mazda. Bought a 2nd hand (6 month old) Mazda 6. After its second service I noticed rust on all 4 wheel arches.
I took the car to a Mazda dealer to have it looked at.
They took pictures of all the arches and agreed there was a problem but they would have to email Mazda direct for a decision. I was told I would hear within a couple of months.
2 months went past and I was told Mazda had serious problems with rust and were devising a strategy to deal with it. Could I please give them another few months.
6 months had passed and still no word, so I contacted the dealer again. They informed me the manager had left and a new man was now in place who was dealing with this and I was asked to visit the dealer again, and again had pictures taken and again was told they would be emailed to Mazda and they would await a decision and could I please be patient!!
2 months past and I had to contact the dealer, who said they had "just" been contacted by Mazda and had in fact been trying to call me (load of rubbish).
I put the car in for the warranty work. 6 weeks it took. When I picked it up I was told all the rear panels had been changed, which I thought strange as I had a slight dent in my rear door going into the rear wing, which was still there after the panels had been changed!!!
Anyway the manager gave a good story of why this was still there and told me it had cost Mazda £3k for the full repair. I sort of believed him.
6 months later and the rust had reappeared!!! Went straight back like a raging bull and dealt with a different manager and told him I was less than pleased I was lied to. This new manager admitted all they had done was rub down the rust and re paint as Mazda had told them to try that first.
I contacted Mazda direct and was given a case number. The dealer contacted me within a day and promised urgent action. I was guaranteed my car would be sorted within 4 weeks.
Well this was 8 months ago!!! I've still never been contacted and haven't bothered contacting them as I traded the Mazda in for my Golf, 5 months ago. Altho part of me wants to phone and see why the delay

All in, the process took around 2 years!!!
I think the fact that my dealer was about a 50 mile round trip away, saved them from me camping on their door step until the work was completed to my satisfaction
Disgraceful service if you ask me.