In reply to john spence:
I'm a sparks and live in stortford. Give me a shout if you need to.
He'll probably bill you for more the 500 quid. Materials are easy to price for, just use screw fix then no argument. Labour you'll have to discuss. Though if he's been thrown off the job he may try, but probably will not expect to be paid.
He hasn't provided the professional service he quoted and agreed to.
To play it safe if you do hear from him again.
Get everything in writing and signed if you can, including any settlement agreement. Telling him your reporting him to elecsa, trading standards, write report on trust a trader etc will probably have him running off anyway.
Regards, Kevin.