False Advertising Item inside box different to picture on box

I bought a top end Gransa Certifugal pump at Builders warehouse last year. I never connected it due to Covid pandemic. Today, I decided to open the box and install it to find that the item inside the box is a yellow lower grade pump while the item advertised on the box is a Blue Unit with a different layout. I am very unhappy with the purchase and wish to return the item for a correct one that I paid for and not something different. Please assist ...