Wrong parts

i bought a clutch and pressure plate for my bmw at Naskar Silverton on the Saturday the 4th of November 2017.. they gave me the wrong parts and when i went back to return it with the slip they refused to return it. the sales person was stoffels and the contact person was greg.. i paid almost 3000 for the parts all i wanted is for them to exchange it and give me the correct parts for my vehicle