I was in Best Buy today to redeem a Reward Zone promo (20% off iTunes cards, expires today but you still have time if you're a RZ member).
Found out from the cashier the store is having an unadvertised sale on iTunes cards. The cashier said 10% off but their web site is 15% off.
For anyone who is a RZ member, she also told me I'd get both discounts (RZ 20% and store sale 10%). But she was having so much trouble applying my RZ discount she had to call a Mgr. And I forgot about the extra, so will see if they'll do a price adjustment. (I'm thinking she was wrong about combining RZ coupon and store sale. There's no fine print on RZ promo saying it can't be combined with other offers, but it does say "Markdowns taken from regular price".)
