University got my classification wrong on my Diploma- Any advice?

I have finally just been emailed my Diploma, but upon getting it I was surprised to see that it said a 2:1 rather than a first. I would have been completely happy with a 2:1 initially, but I was awarded a first via my results page after I got my final marks back around a month ago. I should also add that my final mark does work out to a first (although just above the threshold).

Due to the marking boycotts, I was awarded a provisional grade of a 2:1 as I still had 20 credits of work to come back, and was sent a provisional diploma, which obviously is fine. However, once I got my remaining marks back, my classification jumped up to a first on my results and awards page, as I was very much on the boundary between a first and 2:1 and my final mark managed to get me over the line. Around a month later though, I get my digital diploma sent to me and it says a 2:1. It's so confusing because it contradicts what my award says (I should clarify my award is where people go to see their final grade on results day), as well as what I have worked it out to be.

Sorry for the rambling, I was just wondering if anyone has been in a similar situation and had any advice. My instinct would be to think that its an admin error but I can't help but doubt myself.