My son put a long pin through plasterboard and made a hole in plastic pipe for the central heating in his flat. We cut a small hole in the plasterboard and he covered the pin hole with resin. This has set hard but unfortunately there is still a very slow drip from the repair. I thought about cutting the pipe and inserting a push fit connector, however having used calipers to measure the OD of the pipe we find it is 12 mm. [I had thought the system was micro bore]. I can't find any 12 mm fittings. Any suggestions gratefully received. [He tried adding a little more resin but it still leaked]