I think we always hear the bad but never the good
I ordered from batch 5 (missed 4) used my 10% coupons but accidentally paid to my batch 1 payment address.
emailed Bitmain and they had the issue fixed within 6 hours (whew!)
Great customer service. I could have lost BTC on that order due to my own stupidity but Bitmain fixed it for me.
edit: THANK YOU BITMAIN
Youre right of course.
On the other hand, previosuly BITMAIN has accepted purchases on S2 with coupons that had expired. Was very friendly of them.