I've never had professional oven cleaning before (always just did the horrible job myself), but, following recommendations on here, called in Hither Green Oven Clean. Matt came yesterday to tackle my 15 year old oven and... OMG! It literally looks new. Really worth the money. It cost ?60 for my double oven and he just worked nonstop for about 2 hours. You really couldn't get that same result yourself. Plus, he was just a really sweet guy, easy to have around, turned up exactly when he said he would. If I could find someone that good at their job, and nice to boot, for all the house maintenance jobs that crop up, I'd be very happy. Still looking for a similar plumber/electrician... :(