Hi guys
Today I would like to talk about a situation happened to a friend of mine and to ask for your opinion.
He had to travel far from home and his Felicia 1.3 MPI started suddenly to misfire badly (on one cylinder apparently). He called me and asked for help. He is a normal guy with little knowledge about engines. I couldn't do much on the phone, other than tell him to check the spark plugs and listen for any strange noise. He called me later and said that all looks and sounds fine. I advised him to go to the nearest car workshop and let me know what they suggest after diagnosing the car. He didn't call me that day so I presumed he solved the problem. Two days later he came with his car to my garage. The engine had the same misfire. He told me the mechanics at the workshop scanned the computer and found a lambda sensor error code. They claimed the car needs a new lambda sensor. My friend agreed because the mechanics said they were confident it is a common problem and it only takes an hour to change the sensor. Well... as you would have expected the sensor put quite a fight and three hours later they finally returned the car having a new sensor. Except the engine had the same misfire 
My friend had to pay for the sensor and labour. I checked the engine and found a bent intake push rod... I replaced it, adjusted the valve clearance and no more misfire.
So here is my question: how do you deal with this type of situations in the UK? Who pays for a bad diagnose?