yep, the work was all new and originally done about 6 months ago. i called him back out last week as there was a massive water leak in the plumbing and a gas leak behind the cooker. new boiler and cooker and pipework to an extension.
the cooker joint just needed tightening, the plumbing hadn't been connected properly under the concrete leading to the large water leak and lack of pressure in the boiler (i think it had been leaking slowly since installation and then just completely failed). in trying to mend the plumbing, he put a chisel through the gas pipe and mended this (on friday) with a really messy solder blob. looks really bodgy which is why I did some google research. also when i checked the metre, there was obviously a small leak still, so i did the soapy water thing around the new pipework coming from the metre that goes into the garage and there's at least one leak I found in this work too.
in short, i don't trust this man to come back and sort this out - i think he would if I called him but I'd rather pay someone else to sort it out and have peace of mind. i spoke to gas safe this morning and they said I should make a complaint and he'd be made to fix it - but I don't want him fixing it, so I think I'm just going to pay for someone else to do the job instead.
my main worry is the plumbing to be honest, as the gas work is mostly accessible and hopefully can be fixed, the plumbing under the screed, if that goes again (in a less accessible place), the whole extension floor will need to come up!