Well there really isn't much to tell except that the matter has been resolved.
I sent the feedback/complaint to the company which handled the redemption program for Microsoft promotion late Monday night, cc-ing all the relevant parties (Microsoft SG and USA, Ingram Micro and SiS Technologies). The GM replied to my email on Tuesday afternoon apologizing and agreed to courier the vouchers to me that day.
He came and we talked about what happened that day and how the matter could be resolved amicably if his staff was trained properly on customer service. He agreed and said all staff was actually briefed to honor the timing stated on the brochure for Microsoft promotion since the brochures were already printed. He said I was the first Microsoft customer to encounter that, I am not sure how true that was since his staff said I was not the only one who dropped by after office hours.
In any case, he made a personal trip to my office to drop off the vouchers and he also gave me a $10 Tony Roma's voucher. Showed that he does know what to do to try to salvage the situation. So the issue has been resolved and I wish him luck in hiring staff who will be more pro-customer service. Other wise it will be tough for his business to succeed.