I "FINALLY" somehow got Expert on this level after a week 1/2, don't know how, but am very happy!

Does anyone know how to get expert on last level in the Spring store (1st store)? You need 8000 & I've managed to get 7985 as my highest. I've tried everything and I think you need 26 customers to do this, but no matter what I do I only get 25 in the store. This is sooooooooooooo frustrating. Any help/tricks please before I pull my hair out