OK I couldnt wait for the return call in 1 - 3 days so reformatted myself using the steps below
Hold play/pause for 5 seconds (this will show E-00)
Press TVDrive (this will show E-01)
Press -Ch 4 times (to show HDD4)
Press OK
Wait a few minutes
I now have 80 hours free, all recordings deleted and planned recordings too. I must admit I wasnt convinced when the TW rep said I shouldnt lose existing reordings when the techie talked me through it. Especially when I noticed the following quote in
http://www.blueyonder.co.uk/assets/pdf/14158_tvdrive_troubleshooting.pdf
"Special Note: In some cases it maybe necessary to reformat your TVDrive. Customer Care
will advise if this is necessary and how to go about it. Reformatting will mean that you can
hopefully resume normal service fairly quickly without waiting for an appointment for an
engineer to visit. However, reformatting can result in the loss of recorded and planned
programmes. We suggest that you copy any important programmes to DVD/VCR (see page 21)
and make a note of your planning recordings before reformatting or before an engineer visit."