If your sink is blocked in Winchcombe, Gloucestershire then there are a number of methods that can be used to unblock it. The first thing you should try is using either a plunger or drain snake. If this does not work then you may need to use vinegar and boiling water or bicarb soda with hot water as these create an alkaline solution which helps dissolve blockages inside the pipes; let this sit for about 30 minutes before flushing out with clean cold tap water. You could also get hold of specialist products designed specifically for clearing blocked drains from DIY stores etc., but always make sure any product follows health & safety regulations, so it won't damage your plumbing system further down the line. Another method if all else fails would be hiring professionals who have specialized equipment such as squeegees and powerful hoses to clear away built-up debris quickly, and effectively they will likely also provide preventive maintenance advice once complete!