Have you had to cancel a booking because a dog's demeanor was different from the m-a-g?

Hello. I had a booking at 11 AM on Wednesday, May 29 and had done a m-a-g on Sunday, May 26. The dog I was supposed to be walking is a gem when with her owners and I even had a good, short test walk with just me and the dog with no problems. Once Wednesday came around I got to the location and once inside started experiencing aggression/fear aggression from the dog and no matter what I tried there was no getting better. Spoke calmly, got down to it's level, and even tried treats to no avail. I had to leave after a while and told the owners that for my safety and for the dog's that I'd have to cancel but that I'd help them find someone else immediately. While I haven't gotten a reply back as I type this has anyone else had to do this too? Did I cancel too early? Should I have waited or tried/try again? Any answers are appreciated. Thank you!