With ovens there is a lot to go wrong too..
I started off by cleaning and repairing ovens with my dad.. He's a catering Equipment repairs and service geezer.. In theory great, but when you come to a worn door, that just doesn't want to come off, or an oven that's seen better days, you get the brunt..
MY oven is caked on, no amount of cleaning is ever going to get that clean and spotless, however we're happy as we know its "clean for use"... I have been trained on the job over many teenage years how to do it, but it is graft.. really is (skinned knuckles galore)
I looked and some companies change about 1500 for training, which includes fitting a soak sink in the back of your van.. that renders half your van unusable for a business that will make you less money..
There is a guy on Facebook, (yes i know).. that's offering a single oven and white goods clean for 35 quid.. That's a bargain price, I nearly rang him when i moved house! Now if that oven does take an hour and half, inc travelling etc, he's looking at 20 quid for an hour.. Much less than CC'ing..
However I'm a stingy bugger and for the £65 he would quote for my 2 door range.. I'd rather do it myself..