Contractor Broke Pipe -> Water Hammer

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.
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