Is this only happening when they open a tap. ?
If so may be more like a problem at the tap itself as well as high water pressure. Not just the pipe securing.
You may bolt the pipes down but the vibration will still exist if it is starting at the tap washer and moving along the pipe as a wave. The hammer effect and wave is caused by the seat of the washer vibrating up and down at the taps base. Thus causing a ripple and noise effect along the pipe
May need to replace washers with anti hammer spring types and grease up tap handles and washer shafts. Or install a reduction valve or anti hammer valve.
I think the plumber is playing with his pipe if he thinks just bolting down will fix it
Washing machine taps are also a common problem for this type of hammering.
Try a different plumber.
Search "Water Hammer"