I am currently in a similar situation and wondered if you can give me a bit of advice.
https://www.consumeractiongroup.co.uk/forum/showthread.php?472364-Advice-needed-Claims-management-company-court-case&p=5087639#post5087639
Like you i accepted a hire vehicle after a non fault accident and told auxillis/principia that i was not in a financial position to pay for a hire car myself upfront.
I don't consider myself to be in a financial position despite savings accounts,
as the savings are for a purpose and i didn't think that it was reasonable for me to go into my savings to foot the bill for a hire car,
with no idea what the cost would be/when i would be reimbursed.
Principia are still having issues claiming back the hire car charges from the defendants insurers and i am at the stage where i need to provide bank statements.
If you don't mind me asking,
how has it gone for you in terms of having savings in the bank?
I can justify the reasons why i have sums of money in various bank accounts (saving for a wedding etc),
but do they take this on board when you submit all of your financial details to them?
Any advice is much appreciated as i am stressed the death!!