I have been tasked with acquiring raffle prizes for a local gala. Having sent out over 100 letters plus about 25 emails, I have managed to get a few prizes. The responses are mainly from emails or hand delivered letters. I haven't had any response from over 90 of the lettered companies. I am considering a follow up phone call to some of these companies. My AIBU is do you think this is a good idea or does the lack of response mean they won't be donating and I'll just annoy them with a phone call? If I do call how long should I wait after sending the letters?