Have you actually agreed a jointly instructed expert yet?
If not, agree to any of the 4 she has suggested, given they are suitably qualified (unless you believe any aren't independent), and point out that you are awaiting her draft of the letter of instruction, so that the instructions can be agreed in order for the expert to be 'jointly instructed'.
The aim is to do your best to follow the court's directions, while not allowing her to tilt the expert's instructions in her favour.
Use neutral language, but you want the expert to clarify the main issues for the court ; was the initial installation by you done to a reasonable standard of care, quality and skill, and in accordance with the requirements of the contract ....
post 3 believe PB.
one of the reasons im gonna look at the statements carefully just to check
the original idea was no DN issued but this looks like that's not true.
but the devil is in the details with MB
they always make mistakes somewhere.
I will await the court's instructions.
It is unfortunate if you haven't kept copies of the letters you have sent me, but if the court requires me to 'file and serve' copies of those letters (as part of assessing if you have complied with the court's instructions), and of any correspondence I have sent you, then I will of course comply.
If you desire a copy of the judge's order, I suggest (rather than asking me to provide you with a copy - where you might challenge it's authenticity), that you should approach the court for one, so that the details (and its provenance) are clear for you.
The court can't see such a reply as obstructive, you don't have to do her dirty work for her, and if it riles her at the same time : so much the better - let her claim "foul!", but the court won't see it that way ........
If the court does make such a 'file and serve' order, then make sure you comply with any deadline, but file and serve close to the deadline, so she can't create an alternative and file it in time (in response to yours).
See if any other contributors have views on this, or any alternate reply.
Ah now I see they sent a DN, I am afraid game over. The only thing you could do is apply for a time order, which if successful will permit you to extend the repayment time and thus reduce y repayments, details would have been on your default notice.