Background Check Worries
Need some advice. Recently got a FT offer for a top firm with just 1 problem: Did a 'spring intern/week' type thing at a BB (a UK/Europe thing for the Americans here not familiar with it) in my first year which showed up in my background check and the third-party background check company is requesting for alternative contact details at the BB so they can verify but the BB HR is refusing to verify it because it wasn't a formal internship and it was unpaid (no spring-interns/weeks in the UK are paid). I have all emails and confirmation of my acceptance onto the program and time there, will this be OK? Essentially the background check company cannot conduct external verification directly with the firm and will have to rely on my personal evidence and emails for this.
Please help, am freaking out about this now... don't want my offer to get rescinded..