Sold me an Incomplete engine

AL Nowa Trading T/A Mr Engine sold me incomplete engine which I sent back after discovering that it was missing Starter and Computer box. I paid R25 000 for the engine. When I returned the engine to them they claimed that they sent me a complete engine and paid me back R25 000 less R8 000 for parts that I complaint that they are missing. I would like my money in full as I did not pay for an incomplete engine and my car is still stands still because it needs an engine and I would like to source an engine with the new suppler who will give me my money's worth.