changeing price on old stock on racks

Went into Clicks Malmesbury and took a South African product off the rack. Checked the rack price and by the time I got to the till the price had increased by 33%. the staff were busy altering rack prices all over the shop.needless to say i spoke to the supervisor and paid the rack price when I asked to see the manager and complained about what was going on and general bad customer service. I was listened to by the manager but did not get a satisfactory answer why a old product on the rack can be suddenly increased by 33% \THIS IS A BIG INCREASE\" and how can they do that. Alfred Van Rosenveld cell ***"