Shops and aquarists rarely see eye to eye. Do not listen to advice from the shop. Having said that, if you have not opened the Hikari, see if they will take it back in exchange for a better product. It is not that Hikari will poison your fish or something, obviously not, but when there are better alternatives it is best to use them.
I don't think it's possible for refund now as it's booked for delivery but I will try to see what I can do. Looks like they also sell New Life Spectrum pallets and Fish Science Worm Pallets so will see if I can try to swap for those.
My current stock (x15 neon tetras and x8 peppered corydoras) don't seem to feed much. Just tiny amount of TetraMin flakes twices a day and 1-2 Fish Science Corydoras tablets.
Any more and the feed usually lies on the substrate. Will be interesting next week as we are expecting x10 Odessa Barbs, x10 Cardinal Tetras and x10 Panda Corydoras.