I also had the same "problem". What I did was leave a comment in their feedback asking that they stop sending me the coupons. "All you're doing is tempting me

I also had the same "problem". What I did was leave a comment in their feedback asking that they stop sending me the coupons. "All you're doing is tempting me to use them against TOS" A few months later I received in the mail a $100 voucher usable with existing accounts.