Manufacturer Minimum Age will not update

Hi, I have started selling a product Amazon.com that I originally sold (and still sell!) on Amazon.co.uk. I have submitted safety certification for this product (game) but for some reason Amazon.com thinks the minimum age of the game is 84 months when it is actually 96 months. The listing in the UK has 96 months as the correct figure, and this screenshot from Amazon.com shows that 96 months is there in the back-end too - locked in! The listing displays 96 months on amazon.com! However for whatever reason Amazon's system/seller support insist the listing is down as 84 months - this therefore doesn't match the safety certificate, which keeps getting rejected. And now my game is about to get de-listed with inventory becoming stranded. I've tried seller support repeatedly, deleting and re-listing, uploading xlsm and am at a total loss on how to move this forward.

Can anyone offer any advice?! Pretty desperate at this stage.