Just as a contrasting report on how crap halfords are, I (stupidly) took my car there for a service back when I was young and foolish, however, I had only just joined the world of work and therefore wasn't earning bucket loads, and just got a mk3 1.6 litre rolling stones special edition golf, I took it there becuase it was cheap for a full service, ?120 if I remember rightly probably about 3 or 4 years ago now, picked the car up it was fine....next service due 10,000 miles later and the garage I took it to (not halfords) rang me telling me that the last person who took the sump plug out cross threaded it and basically the screw just dropped out as he unscrewed it, therefore the screw was knackerd and so was the thread on the sump.
He said I can do 1 of 2 things - bodge repair it, which will hold but it will cause probelms next time or get a new sump, the latter option i went for. The car was in there for 4 days (admittedly it was over a weekend, 2 days of it) and a final bill of ?330 for a ?90ish service it should have cost.
I went back to halfords with the sump, this is the happy ending, and they refunded me ?150 cash! I shouldn't have been so tight to start with, 40% of the staff were the rejects I went to school with.