It might not be the right place but I'd just like to stick up for the local Sainsbury's a bit! Each time I haven't been able to find something, the staff on the shop floor are always able to tell me where it is down to the exact shelf, and even give me recommendations (e.g. the right type of brown sugar to buy to make banana cake, and types of herbs to season salmon with), which is something I can't say for alot of other supermarkets or even department stores. The place might be a mess with boxes all over the floor, but I always get good service there.