I can finally provide an update on this. I complained to Virgin which wasn't initially easy as the form insisted I include to and from stations which had to be on the West Coast, which obviously Basingstoke and Waterloo are not. Anyway I put in 2 stations and then explained in the text why they were irrelevant. After a long delay I received an email into which someone had cut and pasted all the small print from their terms and conditions, and blamed me for the error. I was particularly impressed by the suggestion that once I had been sold incorrect tickets, I could ring them up, pay £10 a ticket and have the error corrected! They did not make any attempt whatsoever to investigate their error.
Anyway I wrote them a stinking email back telling them just what I thought of their response, their ridiculous suggestion and the fact that they had ignored the fault altogether.
I have been away but have received a letter from Virgin which appologises for their previous response, the inconvenience and accepts that they do have an error in their systems which they says has been passed to the relevant team for further investigation. They have also included a £15 Rail Travel Voucher (more than the cost of one ticket), so I guess I am satisfied. Hopefully they will fix the fault.
So my thanks go to everyone who assisted here and by a PM