For those still waiting, I've FINALLY had a reply. No apology, just said the system took longer to process (coincidence that I now have my TH at the same time as their reply!)

The reply:

Hi!

Your purchase ID: XXXXXXX has been processed successfully. We've checked and everything is in order. Most likely it took the system a little longer than usual to process the transaction.

Thank you in advance!

Best regards,
Alice
HashFlare.io Support Team