We called the gas emergency line due to us being able to smell gas. Their investigations discovered that the leak was coming from one of the rings on the hob leaking due to the knob getting stuck and not turning off properly. The hob does not have an isolation valve so in order to prevent further leaks the engineer has turned off the gas at the meter, leaving us without heating and hot water. We have since cleaned the knob and it appears to work properly. The problem we have is that the hob was not fitted within regulations by the previous owners of the house in terms of how far it is away from vertical surfaces (it is only 40mm away from the back and side wall although these walls are both tiled). Would a GasSafe engineer check the hob over and make any necessary repairs? Or would they insist that it be replaced to regulations?