nectar card Sainsbury's vouchers

I no longer want to receive Sainsbury's (paper) vouchers in the post. I never asked for them, only go there very occassionally as it's not near me. Is it possible to not receive them or do you have to receive them. I rang nectar quite a while ago and they said it's not possible, you have to have them if you have a Nectar card. Tried changing marketing preferences online but paper vouchers are not part of the options. I'm thinking of sending them a message that I want to leave unless they stop sending me the vouchers.