Disappointed

I got a R100 voucher from truworths via sms but i was told that i cant use the voucher on a sale item.the voucherdid not have terms and conditions that you dont use it on sale item,its like it is coming out from the teller's head.I find the store not realistic because the message could have stipulated terms and conditions in black and white.i was made a laughing stock of at thetill when i was turned away with the voucher.