If anyone is still having problems with the signal strength, try turning off 3G and Location via Settings section. I constantly had only 1-2 bars, but once turning them off my signal has improved massively; now getting 5 bars 90% of the time. I reckon it is more 3G affecting the signal, but try with both off just to be sure. If it works, then turn on 3G only when needed. Apologises in advance if this is already tried and tested, it just worked for me so thought I'd share.