Thanks for your reply ACO. So far we have done everything you suggested except for putting out the food/items with our smell on them. I suspect raccoons will get it before Sunny does, but I'll give it a shot. It's just so foreign to me that he isn't coming when we call him.
Our local shelter never replies to messages, even the voice messages left for them. I have never had luck getting in touch with them and it's very upsetting - even more so now as it's a lost pet for me, not one I found. It seems silly for them to not answer when they are there. Tomorrow all the vets will be called and more posters will be put up in suitable locations. I have already sent a message with pictures to the local society, and one vet office which keeps a website and has a lost/found page. The OSPCA says to contact the local shelter - the one which never replies. That's government for you. We went door to door yesterday but had no luck. We did come across two women who feed stray cats. They are within a conceivable distance from our house, so hopefully we'll get luck there.