Pick and Pay Facebook specials

I am a 67 year old pensioner, that for past 5 years are a daily shopper at Brentwood park Pick and Pay. Brentwood park Pick and Pay runs Facebook specials in store. When you get to the pay point you need to show your Facebook page to get the discount. For me as pensioner every cent i can save is a help. I dont have Facebook because we did not grow up in a social media area. I would like to as the Consumer protection act is this legal. Can you have specials for only a sellected clientel. Its very strange as our retirment village is across the road from Pick and pay. Because i dont have Facebook i need to pay more.