In reply to colly64:
The signal enhancer thingies are black magic. You have as much chance of influencing reception by sticking pins in an effigy of the MD of T-mobile.
Orange and T are on 1800MHz which is not great for getting round corners and through walls. Many phones are really rubbish for receiving radio signals. This is unfortunate since some users still think that is their primary purpose. Most users think that their primary purpose is to make them look cool and trendy.
If you are on Vodafone and have a 3G-capable phone and good home broadband then you can fix this (Sure Signal). Otherwise, tough luck.