I overpaid Bitmain for an order last week. After contacting them, I received a message back that their finance department would take care of it. Several days later now and I've heard no word since... does any of you have experience with a refund from them, and if so, how long did it take? Thanks.
Give them some time to review the account... If they said they referred you to the finance guys, they might get back to you slower than the web and delivery team as these guys are workings like ants *pun intended :-) I am sure the finance is team is much smaller than the production team.
My recommendation is wait up to 5 working days, send an kind reminder regarding the refund, or ask if they could send you another miner (obviously you can top-up the price if needed).
Let us know how it all goes.