Not accurate.

this is the second time in as many days that I've found trolley not to be accurate. In the last couple of days Sainsbury's have had Oatibix flakes discounted to £3 per pack. Usual price is £3.80 per pack. why isn't trolley picking this up? It is not as if it's a sudden change because the change happened a couple of days ago. I don't hold much faith in this app anymore