Export your July statement up to today from your banking app if you're able to, including the £12k top up. Then combine 3-4 months statements + currency conversion screenshot and send it back to them.
Personally, I would top up the account to at least £12k to be on the safe side, then resubmit the bank statements along with a currency conversion from today.
Actually, £11,500 is juuust over the 500,000, and a random currency fluctuation could take it below. Attach a currency conversion from google with your bank statements as well.