HireRight issue

I have no one else to ask, but hoping someone else here has had  "close encounters of the third kind" with HireRight. First of all, it is my mistake I did not research their background and was not aware they have had several lawsuits so this one is on me. I'm being made perm from temp in a bank and on my CV I have included a Student society I was an Associate member of. HireRight are now asking for "contracts, payslips or tax records" showing I was part of this society. I input this as non-paid in their online questionnaire so did not expect to be asked for payslips. I have tried speaking to HR but they just tell me to give HireRight the requested info. Is there anything I can do to get through to them? The application shows as pending and I don't have employment records for it as this was not paid. Ironically my finance work history is perfect and that part has been completed. I tried emailing them but no reply. 

It will now risk showing as "Unverified" on their reports so obviously paranoid my offer is at stake over this. Can anyone advise at all ? Should I tell them I don;t have documents and they leave as unverified ? But then HR may think this is a red flag. Not sure if a letter form my former team would help. Any advice is greatly appreciated I am losing sleep over this, I can't eat and all I do is google for info/cases similar to this one.