Invite customers and press. Leaflet rival stores. Trolley runs - Fill up trolleys with goods containing soya and maize. Be polite to checkout, demand to see manager. Leaflet queue to explain the hold up.
Trolley stops .
Again fill trolleys with GE food. Put contaminated signs on trolley then leave around. Redistribute contaminated brands around the shop. Creating a biohazard zone - Quietly fill a number of trolleys with contaminated goods. Take them all to one part of the store and restock them on same shelves - a contaminated food aisle.