Coolant Leak Issue

[KuaiThunder]

The water pipe broke last week during a night out and have the car towed to a shop. The shop changed two water pipe. According to the shop one pipe is cut from the friction between pipe and something and the other seems worn out. The shop also told me that he has put out all the air in the system and ask me to check the water level after the car cool down after I get home just to be sure.

After letting the car sit more than 12 hours I open the cap on the overflow tank to look. The moment I open the cap water start washing down from the bottom of the car (right hand side). I also notice the coolant is at the top of the overflow tank. Initial thought was the shop overfill the coolant so I close the cap and start the car to see what happen. About 3 minute or so the coolant is start leaking again and this time from the left side. Coolant low warning flashing now.

So it get tow back to the shop and two days later the shop called and say not able to reproduce the situation. Again I drove the car home and this time I am wonder should I open the cap.....The drive from shop to home (about 25KM) go without any issue on both time. Water temp look normal on both time as well. Also, the coolant leak out seems clean.

Any suggestion what happen? It drive fine so far but worry it might leak while I am in the middle of the road.

Boxster S 2001 Tip with 95K KM. New water pump in about a year and half ago.