I would be interested to know how do they recover the oil, how do they know that all the oil has been removed remembering that the oil travels around the system as a fine mist and adheres to the pipework. When they put their recommended amount of oil back in the system how do they know that the system is not now overcharged with oil and any guesses what can happen when a refrigeration compressor has too much oil in it, I have seen compressors totally destroyed and internal pipe work full of oil, what happens when the problem is a blocked orifice tube or expansion device which can give short of gas symptons to the inexperienced or machine operators who do it from a manual, they will then add more gas and oil as well as the blocked component can hold back gas and oil so when they put an additional charge in on top of whats already in the system, thats it, 1 x compressor destroyed or when the guy who is going to repair the system opens up the system it is full of oil, compressor, pipework and all components.
£25 is dirt cheap and I would not expect much for that, they are obviously using your cars as guinea pigs while they gain experience dabbling with your pride and joy ready for the summer . I am glad I dont touch cars any more, too many get rich quick cowboys dabbling now, you know what they say, pay peanuts, get monkeys.