Try to get it in writing (text is fine) that he has said that he will come back Sunday or you can get someone else. That would be enough to allow you to get someone else and for him not to be able to claim in court that you were in breach of contract but not allowing him to finish.
You cannot sell his tools to recoup any deposit which you have given him.
If he will not return deposit, then you will have to sue him in the Small Claims Court.
With regard to the defective work, you are entitled to recover from him, any money over and above what you’ve paid in respect of the value of that work, if it costs more money to put it right.
For example, if he lays a patio and he quotes you £2000, £1000 deposit plus £1000 on completion.
He makes a mess of the job and the whole thing costs £3000 to put right, you are entitled to recover the extra £1000 from him, so that the whole job only costs you what he quoted in the first place.
I suggest that you put the last request in writing, that if he does not arrive by Sunday to finish the job, you will get it done elsewhere but that you want your deposit back.
It’s important that if it does get to court, you have quotations for getting work done (not estimates, quotations) and a report on the defects the work which has already been done.
After the Sunday deadline, you are under a duty to mitigate your loss and that would include getting the job finished, paying the bill, and then seeking any repayment from the tradesmen.
Just make sure that he’s had ample time and you do warn him that unless he completes the job within, the next seven days, you will be taking him to the Small Claims Court.
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If you’ve already told him that he can come back today and he does, then let him. If he screws the job up, you can still sue him for the cost of putting it right.
If he doesn’t come today, he said that you could get someone else and it’s not unreasonable, even if he had not said that, for you to get the job done because you can’t wait forever.
If you get someone else in to finish the job after today, I think you have done sufficient to fend off any breach of contract claim he may bring. He might try it, but I can’t see it succeeding.