A purple picture is usually the result of either a faulty HDMI lead or faulty HDMI socket.
If you've tried on 3 different TV's and with different HDMI cables then it looks like the V6 HDMI socket is faulty and you would need to contact the faults Team for a replacement.
Have you tried signing into Service status at the top of this page and run a test against the TV box? By doing this VM should be able to send a signal to your box and try to repair it. I very much doubt it will find anything wrong with the box. Following this procedure may make the next step easier.
You will need to call 150 from a Virgin landline, or 0345 454 1111, options 1,1 and 2 (Faults) butbest to call at 8am to avoid call queues
When calling Faults you will go through a series of questions/tests, but because you've tried via the above method then an agent should pick the call up, however if they don't then call back around 10 minutes later and you should get through..
Or you could try the text messaging service. Just send a text with a description of TV Faults to 07533 051809. Your message will go into a queue and a representative will respond to you as soon as possible.It may take a few days.
The other alternative is to wait for a member of the Forum Team to pick this up, but that may take from a few days to a week.
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali