The reason he's put so many joints in is because they have gone from 15mm to old half inch on the cold side and three quarters on the hot side back again on the other side,he should of just cut it all out and started again.
Clipping the pipes to the floor,bet those service valves aren't full bore either...
The broken stack could of been fixed correctly with a timesaver cast iron connector,ensign do a similar product,alot neater than those rubber bands...
Basically its a £150 in and out job,can't believe he has the cheek to ask for £650
... Brass neck...