Thanks for the prompt reply BankFodder.
We paid in 2 stages (part upfront and part during the works) by bank transfer, which means we have his bank account details so I'd assume a bank levy could do the trick.
I found his address and it's confirmed by the fact that the registered mail was received and signed by him whom also mentioned it in an email.
All we paid for now is £530.
In order to make sure he'd be updated I also sent him texts, just in case he wouldn't be checking his work email.
You are right, I should get a quote by another trader to understand how much it