Thanks for writing in! Happy to look into this promo for you.
It looks like the promotion you're asking about was used on a recent trip on September 15, 2015. I've resent you the receipt so you can take a look at the details, but the original fare was ฿162.00 and with your ฿162.00 off promo, your trip is free of charge
You can also login to your account at uber.com to see your recent rides, resend yourself receipts, and view any promotions you have on your account.
I also collected some information here that I thought might be usefu