samsung galaxy ace poor signal on o2?

i have been on contract with o2 at my current address for years without any issues. however i recently bought a new handset a samsung galaxy ace nad since then i have hardly if any signal 3 different people have tried to call me today with out getting through. is this a Galaxy problem as i never experienced this with my last phone a vivaz, and have not changed providers or services at all.

anyone any ideas on what i can do to improve service i either have none at all or if i'm lucky one bar.

Sorry cant help but my daughter had a nokia touch screen with o2 and had terrible time for signal and last week she upgraded to samsung galaxy with o2 and she has no problems.