I am concerned that bitmain has my coin but havent responded with a confirmation that I paid (even though my payment shows it went in 5 minutes after I ordered it) - does this mean they are going to take my money and not give me the product I ordered?
I have the same problem today, I paid by BTC at around 2:30PM , it is now more than 3 hours later and my order shows up as unpaid and expired. I used my blockchain.info wallet because I think Bitmain also uses Blockchain.info wallets... anyway I emailed them and opened a ticket but have not heard anything back. I do have screenshots of the transaction and of the block explorer showing the exact sum in their payment wallet.
don't worry yet. if tx is on the blockchain, they will adjust it manually within 24 hr.