Depends on the terms.
-If it is buy 2 and get 1 free-you can just ask not to get the free one.
-When I bought my original Lavender Albino ball python the breeder had a promotion for a free matching Het Female to go with any recessive male purchase. Good deal for me.
-I won a door raffle prize at an expo and the award was a $100 gift certificate to a vendor AND a red-tail boa. I asked for them to keep the boa and give me the certificate and they said it was a 'package deal'--so I was forced to decline.
-One of my distributors gave me a gift box during one of our exchanges. It was around Christmas so I thought it was cookies or something. After he left I opened it and inside was a deli cup with a vine snake-I was super mad. I made him drive back to take it. I told him not to give me any more 'gifts'.