Specials not going off at till

Im writing this as a final straw. Almost every other shopping trip there is an issue with the pricing, waht is on the shelf is different to the till. Most of the times I do check and get it corrected there and then, but sometimes Im in a hurry or I forget, it shouldn’t have to be a constant thing of checking every little sale item was discounted. The latest mishap I found out at home, I posted on their Facebook page hoping to get assistance only to find my comment deleted and ignored. There was a manager’s special ( no end date, I even took a picture because that has become the expectation) only realised when I got home that it didn’t go off. The second star is for the (mostly) friendly staff.