Hi there alpine*,
If you've only ever had poor or very poor signal at home, then this wouldn't really indicate a problem with the mast. The reason I say this is because most mast problems are resolved in a matter of days.
How long have you been a Vodafone customer?
I've checked the postcode contained within your profile and 3g coverage for this area is good/excellent. The serving site is reference 46893 and is just to the North East of you over at Sandy Lodge just off Hambro Hill (hope this makes sense?).
Anyway, I've checked the site stats and the call and data success rate is hovering around the 91-93% mark so nothing unusual there.
Have you tried the dongle in another machine and also in a different location?
Also, it's worth trying your SIM in a handset, browsing a few pages, then replacing in the dongle, just because it'll refresh your SIM on the network in case there have been any glitches locally in recent times.
Let me know how you get on with these suggestions.
Cheers,
LeeH
eForum Team