Bad attitude, No Customer Service and Rude

I went into a the store at Jabulani Mall and had the worst service ever, I went to buy some groceries and also had a voucher from Investec that was addressed to me and sent by WhatsApp and my ID at hand my cashier was polite and all but there was a women by the name of Nonhlanhla who turned me back with a rude behavior and said I should look for an original sms from wherever I got this bday voucher from *** should I get the original sms if I have the original message on my phone. Im a very upset client and feel I dont want to buy anything ever at Woolworths South Africa. I was supposed to be happy shopping from Woolies but this was the most terrible day ever.