If it was a shop that states to call and visit Monday - Friday, they were wrong to unassign you after you got the shop assigned on a Friday. If it was an "anytime" shop, they would have expected you to make call attempts on Saturday and Sunday, to secure the 08/12 date for touring. If it was a "shop anyone," that is doable, to call and visit the same day. If it was a target shop, you cannot be certain the target would be there or even answer the call on the 12th. You did not provide any of these details in your post. Some leasing offices are not open on Sunday, though, which would help your case. And some show by appointment on Saturdays. Either way, you stated you would call on 08/12, and they accepted. Or did you actually state you would call "by" the 12th? It seems like something was missing in the communication.