I've a standing offer out to friends of mine. They can drive their car over to my place (pre-arranged, of course) and we'll change their brakes together and all they have to pay is the cost of the parts (which is usually much less than they expect).
A few of my mechanically inclined but lacking confidence friends and a few of my other broke as a joke friends have taken me up on it over the years. Most can't believe how cheap, fast, and easy to do/hard to screw up it is. Very few repeat "customers" though. :(
In the fridge case, it turns out he had already ordered one for delivery in a few days and had already mentally parted with the money, so didn't want to fix his and call to cancel the order...
I'd expect "few repeat customers" to be a good thing - after pairing on DIY repair the one time, they have the confidence to do it on their own the next time.
Also, a lot of people complain to generate conversation, not for the 2nd opinion they get.