Our concrete contractor broke a PVC pipe while doing our front patio.
After shutting off the water, they removed the broked pipe and capped
as necessary. Since turning the main water back on, we experience
water hammer everytime we flush the toilet in one bathroom. This has
NEVER happened since we bought the house three years ago.

The concrete contractor suggested we open all faucets in the house for
a short time to relieve pressure in the pipes, but this has not solved
the problem..

My question: what recourse do I have with the concrete contractor to
resolve this. If it is necessary to pay a plumber, can I get the
concrete contractor to pay for this? Thanks for any help.