Excel Expert - Concrete Register

We manage a concrete register for inputting delivery dockets, that auto-totals quantities and spend. Currently it adds up the quantities by location (e.g. Level 1) + element (e.g. footings), then looks up the "mix" used (i.e. product) and mix rate ($), then multiplies the quantity x rate. In practice I find this is too easily broken by our teams. I would like to simplify somehow so that it just totals the spend for the location+element and doesn't get too granular about separate mixes.