Double the Difference policy not enforced

I shop at Pick 'n Pay due to the specaials and the rewards program. And raincheck and double the difference makes life's inconveniences easier to deal with. But time and time again, I have hassles with Double the Difference. On Monday 17 June 2019 this happened again. I was overcharged for peanut butter. Price said R 25.99 but it scanned at R 32.49 I received R 6.50 but when I asked about Double the Difference the cashier said that she forgot about it. I was due to get back R 13 which could buy my niece a treat so even a little does go a long way to assist in making hte inconvenience bareable. Even though the policy is printed right above the tills, it is still not enforced. Disappointing