Costs me 0p a minute to call the usa (after3p connection)
http://callchecker.moneysavingexpert.com/
and when I've called an FSS (I think it stands for flight service station but I may be wrong) (remembering the time difference of course , 5hrs behind GMT east coast 8 for west) I've never had a problem getting through, or getting an answer from them , usually very quick and helpful.
BTW the CAA have been helpfull but perhaps a bit more 'jobsworth' on occaison
T2