I was a little bit precious,did a little stomping, and a little ranting...
but I was stressed to find it was full, especially after not being able to find it park etc but the organisers were very supportive and understanding.
I was in the same boat as you, but they let me run it as a training run and to be honest the course although spectacular scenary wise was so tough that it would have been off my pb anyway - so better to treat it as a training run.
At the end of the day - I know how you feel but those people were volunteers and it was for charity! let us both live and learn.
After I calmed down I throughly enjoyed the day - I hope you are now ok.