I'm having a problem with texting just one number. I can phone and receive calls ok and receive texts but any text I send does not get through. I get no notification to say the message can't be sent, all appears to be ok from my end, the message just never arrives. The other number is not a Virgin number. It used to work ok but stopped a good while ago (2 years?) - I changed my phone a few months ago and thought this might rectify the situation but to no avail. Any ideas?
Try deleting the contact/number, then recreating it afresh.
If your phone/account has syncing enabled, delete all instances of this particular contact/number wherever it exists - e.g. in email accounts, phone contacts, SIM contacts, etc, etc. After recreating it afresh, try sending a text.