Oh Chris, I feel for you. I really do. Same thing happened to me exactly. I got cancelled four days before my first scheduled surgery. I was well and truly gutted. I had invested so much into that surgery date, made arrangements, prepared family and myself then nothing. I understood and accepted the reason for the cancellation but I have to say it took a while. I eventually got my op 28 days later because I opted to wait for my original surgeon to do it when he was available rather than get a new surgeon.
Do you know why you have been cancelled? Let them know the difficulty you are having trying to undo all the arrangements you had put into place because of the cancellation. Are you private or NHS. If you are available for surgery at short notice, it might help to let them know this.
I hope you get another date soon. Please, please don't chuck it in. If this is something you have already decided you want then it's well worth waiting for. Waiting is frustrating but the rewards of wls surgery are so worth it, especially if you've failed at everything else.