I agree with Phil. I don't own a garage but I tried this about 20 years ago and never again. I would ring my customers about 2 weeks after a visit and ask if everthing was ok. I got a fair few with customers saying things were ok but I thought the car "missed" a couple of days ago, or "don't think it starts quite as well as it used to" etc. Difference with me compared to garage owners is that I feel I am obliged to revisit the vehicle again, whereas the garage owner simply says "well bring it in and we'll have a look."

The worst case I had was ringing a customer and a distraught lady on the other end of the phone saying that it was a bad time to call because her husband had just died a couple of hours earlier

No, let sleeping dogs lie. If there is a problem......they will ring.

Regards

Pete M