Builder hasn't completed - it's months overdue - what can I do?

I took on a builder, through Rated People, to do a complete renovation of a 3 bed property. In May 2022 we agreed a 2-3 month time scale. Things were on track until July - then work stopped and the builder stopped communicating. I know he had personal problems in both his private and business life. Since then, in response to my pestering, bits of work have been done. It's now, perhaps, 90% complete. But weeks pass inwhich nothing happens. I have suggested taking the management of the work back - he points out that it makes sense, and is cheaper, if his plumbers and electricians finish what they have begun. In addition I don't have others I could call on in that area. I don't know what to do? What leverage do I have? Regarding the finances There is only one payement outstanding for about 4K. He has not asked for it and I guess knows he won't get it before completion. Any suggestions welcome