There will always be unexpected issues, the real test is how you handle them.

The initial call was to stabilize a toilet that was rocking. I diagnosed the issue as a bad toilet flange, and proceeded to replace it. I had drilled three holes for the new flange into the concrete slab, and on the fourth and last hole I drilled through a hot water line.

A geyser of hot water spouted out, and I quickly grabbed a trash can to re-direct the water into the drain. I rushed outside, knowing exactly where my water shutoff tool is, and turned off the water to the house. Then I began the long process of figuring out how to fix it.

I used my hammer drill to drill into the slab, eventually locating the 1/2" copper line. I was able to solder in a new length of pipe, but then read that solder joints in concrete are not a good idea - the chemistry will lead to eventual failure. It's also VERY difficult to get a water tight solder joint when you're working in a small hole. So I bought a Very Expensive press tool and used that instead. Thank you Home Depot for your generous return policy!

After repairing the pipe and ensuring it was water tight, I redid the concrete, then re-did the tile (luckily the client has several pieces of left over tile from the original installation).

It took a while, but the toilet is now rock solid and the customer is very happy. I didn't charge them for any of the work I had to do in between when I hit the pipe and when I got back to the point of installing the toilet flange. Total elapsed calendar time between the first day and the last was Monday to Friday of the next week.