Hi, My plumber and joiner have not co-operated on my shower enclosure and left a small. niggly problem. The old installation and tiles were remved. The plumber installed the new shower tray and enclosure then the joine installed shower panels. We kept the Bristan Artisan mixer on the wall. This has left more of the pipework protruding and there isn't enough thread for the chrome collars to thread on the shower mixer pipes. The collars are only about 20-22mm deep and I need something about 3-4 mm deeper. Any ideas? Can I obtain different collars ? This is very stressful - a good looking shower install but not quite finished and tidy to use. thanks.