I haven't use them, but have you tried the international version? i.e. the +1 or 001. For example, if you are calling a London number in the UK it starts with 020 71234567. If you need to call it from abroad, it's 004420 71234567 or +4420 71234567 - note that one zero is gone. 0044 or +44 is the...
You can always try the Spanish FNAC. My experiences with them have been good, though I send them to addresses in Portugal which makes it all much easier.