pathetic service and false advertising

I WAS SENT A 10% DISCOUNT VOUCHER EARLIER THIS YEAR. THERE IS NO EXPIRY DATE ON THIS VOUCHER HOW EVER WHEN I TRY TO USE IT I AM TOLD THAT IT HAS EXPIRED. WHEN CONTACTING THEM I GET TOLD SORRY FOR YOU BUT IT EXPIRED!!!! HOW CAN IT EXPIRE WHEN THERE IS NO EXPIRY DATE ???? THIS IS PATHETIC SO BECAUSE YOU FAILED TO PUT THE DATE THERE I AM NO LONGER ENTITLED TO MY DISCOUNT ??? SO THEN WHY BOTHER TO SEND IT OUT !!!! IT IS VERY EVIDENT THAT YOUR COMPANY DOES NOT WANT MY BUSINESS NOR MY MONEY !!!!! IN THAT CASE YOU HAVE MANY COMPETITORS THAT WILL GLADLY TAKE MY MONEY I'M SURE!!!!!