When to dump vendor?

When people show you who they are by their behavior, believe them.... At a minimum, this company is demonstrating they have poor customer service and terrible communication skills. I would not want to put something as important as the food for my wedding in the hands of a company like that. Who cares if they are "wildly popular" if they cannot meet your basic requirements for communication and follow through. For the most part, daughter had phenomenal vendors. However, there was one, who from the very beginning, was bad about responding to messages and was not easy to schedule appointments with. Daughter liked her well enough and really liked her work, so she went with her. Not surprisingly, right up to the week of the wedding, that vendor's poor communication was a huge frustration to daughter. Ultimately, she came through and her work (HUMA) was excellent, but she caused daughter considerable stress that could have been avoided. I'd find a new caterer, but after you do, I would send an official notification addressed to the head of the original company and tell them what you experienced and that as a result you found them too unreliable/difficult to work with. After that, I'd leave honest, descriptive reviews that explain you would have liked to use them, but found their communication/follow through too unreliable. (You may not be able to leave reviews on some wedding sites since you may not actually book with them, but you can leave reviews on Yelp, etc.) Good luck!

I would immediately start looking for a new caterer, as I agree with everyone else here, that if their communication is this bad now, I can only cringe at the thought of what it will be like for you dealing with them for the next 7 months.

The other huge reason I think you should find someone else immediately is that time is ticking. Your wedding is approximately 7 months away. If you wait much longer, you may have trouble finding a caterer who isn't booked on your date. So, start making those calls!!