Shipping cost rip off fron online book shop

I bought 3 books online at "Buy Books Online" in 2 purchases for which I was charged 2 times delivery costs. As it turns out they came in ONE parcel, which I percieve as rip off. The delivery costs were R 180, in comparison to the price of the books R150 NEVER again. Interesting how some companies think they can threat their customers these days...