Decorator fitted the wrong coving - what should I do?

Some sort of DIYNot possee, perhaps?

He's already charging you way over the odds so don't offer him anything - £360 for a mornings work? He's only a decorator - a consultant heart surgeon earns less than that.

Tell him you'll contact the scheme and that if he continues to be aggressive you'll not hesitate to get the Police involved. Then he'll be booted off the scheme.

That'll shut him up.

I appreciate all the anxiety that comes with this. However, be confident with the fact that you have all the evidence and you are the one in the right. I would very very calmly reiterate the facts where & when required.

Catch him off guard next time and phone him off the hop. Tell him from the off you are not phoning to get into a shouting match and state that at all times you have been more than pleasant and honest about this situation. Tell them that you have outlined your expectations of him and that given all of this and the compromises that you are prepared to make that it is the minimum of your expectations that he would converse civilly with you in order to come to an amicable outcome on this matter. Tell him that you a not prepared to argue and if he decides to go down this route every time that you speak to him that you will politely hang up the phone and contact him again when he is in a more rationale mood.

If he comes round again to discuss have a male friend there who has popped round or is there for his dinner etc...

Killing him with politeness and kindness, being firm but fair will give him no grounds and he will either succumb or walk away.