I've had the same problem, cap1 have defaulted my account after issuing court proceedings (full settlement just received

). I have written a prelim giving them 14 days to remove, but won't hold my breath. It will cost £150 court fee to issue a claim for it's removal, although I will reclaim this. I wrote to them quoting Section 13.6 of the banking code which means they cannot supply details of the debt to CRA's when the amount is in dispute prior to the issue of the default. But they totally ignored it.
http://www.bankingcode.org.uk/pdfdoc...ING%20CODE.pdf
The account is in dispute as soon as you send the initial letter requesting copies of statements. Not sure but you may be best to wait and see if they add the default before starting court claim and then you can include it.
Good luck, Joan.