Cloakroom nightmare

We got back from holiday in Corfu this morning.
When looking round the house we noticed a damp patch on the wall of the cloakroom by the floor. I opened the adjacent access to the main stopcock and found a water jet going up inside the plasterboard.
I turned off the stopcock. This had no effect on the water jet. It just turned off the supply to the house. The leak was from the side before the valve. I went to the main in the street. The off valve was out of reach 3 feet down the hole!
I called the builder, who was just on his way out for the day. Within 10 minutes he was at the door. 10 minutes later the new floor was up and trunking ripped out. His assistant turned up then and turned off the supply: he has longer arms!
Then they fixed the busted joint.
We now need to wait for it all to dry out and they can make good.
The pipe was probably original. It wasn't touched during the works.