I've found where Truphone have hidden the online support:
Truphone | Facebook
Interesting nuggets:
"the inactivity period is 90 days, after which you'll be charged £2 monthly fee that could be avoided by making a call or sending a text." - that's good.
"data is charged per session in 100KB increments. Minimum charge is 100KB, that is 10c in the USA and 5p in the UK." - that's not so good, big chunk.
Rob