Re: keep getting charged for a picture message to Canada and the USA what is a picture message?
Picture messages are the old MMS ...
Close, but no cigar
Picture messages are Virgin's lazy way of describing MMS. The OP hasn't sent pictures to America, he or she has sent MMS to... somewhere else (more on that in a bit).
There are two (main) protocols for messaging between handsets. SMS and MMS. SMS uses 70 characters, or, by fudging the alphabet (i.e. using only 7 bits per character instead of 16), it can get 160 characters into a message. You can send longer messages, but it's done by handsets splitting into and combining from multiple SMS texts.
MMS is a more efficient protocol for larger messages. Typically this would be for attachments such as pictures, but for anything bigger than a few hundred bytes, your phone may well decide that MMS is a better protocol to use. A long message and/or a big circulation list are as likely to trigger the conversion as a binary attachment.
And in the UK, this is a problem. Because pretty much every carrier charges for MMS even though it uses mobile data. If you attach an image, send a contact card, send to many recipients or send a very long message, your phone may decide to use MMS.
And you'll pay.
As for the OP's problem he/she made the mistake of selecting an email recipient for the messages. The handset converts these to MMS and sends them via a message centre which looks like a US/Canada number.
Jules - look through your text messages for any sent by you at the times you've sent these supposed pictures to America. I would bet money (and I don't have much) that you find texts which you've sent to an email contact instead of a mobile contact.