I can't win for losing on this crap. http://www.cancuncare.com/forum/cancun-info/20514-stupid-walmart.html
I dont know why you want to fight it all the time!? You know how it is, it's just extra hassle and there's enough legitimate hassle without creating more for yourself. Why not just use Pesos like the rest of us do?
I was thinking of times I'd really got angry about things in public while living in Cancun and there's only probably 5 times, but surprisingly 2 of the 5 were at Walmart central, (1 was at Chedraui Las Americas)! Not a good record for Cancun supermarkets! I can no longer buy fish from Walmart after work, which is a shame cause they had the best I could find....