Staff not knowing porcess

Spoke to a lady at Sportsmans Wearhouse Tygervally regarding a garmin watch. she told me if i buy the watch online as i want to make use of discovery's 30% discount on miles I can buy the watch online and recieve an order number. once i have the order number i can collect the watch with my order number in store. I then recieved an email regarding delivery. I spoke to a lady in custmer care and she advise I cannot collect, it takes 3 days to deliver (working days). i am flying out to Aus Suday evening and need to collect the watch sun monrning. how can an store infom a customer, even assisted him to pay online and then later finding out you cannot collect. if this was told to me when i did order online, i would have just went to the store to pay cash.