, yes it is required but does any RGI pull out the oven
Do I bugger @ianmcd why risk damaging a customers appliance, wiring could be crap etc etc but... It is required and the guy paid a good price for the job to be done right. I could except the valve missing on a £70 job but paying the right price you want the job done right regardless.
Sounds to me like the price was never even asked for as the OP has used the before and expected a good job regardless of costs. He hasn't had that but they are now returning to fit at their cost so a bonus and a good outcome for this post.
Hopefully the OP will come back to us after it has been done and let us know how it went and the result.
Jon