It is over £5,000 so it won't be a small claims, so therefore he is in default, and you file the defence clearly stating
On xxx date I sent a CPRxx request - the reply from the claimaint is attached. As the claim total is over £5,000 it will apply to this case and therefore their refusal is an abuse of court process.
As I do not have the details I need to fully particularlise and properly defend this claim I am asking the court to strike this out completely due to the non compliance of a valid CPR request.
I am reluctant to allow the claimaint to have additional time to provide documentation they should have had on filing the complaint. This clearly is an abuse of the court processes and designed to frustrate the proceedings.
This is a statement of truth by XXX
You don't need to do much more than a short defence on this, also sometimes called an 'embarrassed' defence.