Here is a version you can post that is professional, to the point, and doesn't require a name:
I am writing to express my dissatisfaction with the service I received from the front desk staff, particularly the representative who was working. Her demeanor was completely unprofessional and unwelcoming. When I tried to ask a question, she responded with heavy breathing and long, unprofessional pauses ("uhhhs"), making the interaction feel awkward and rude.
The front desk staff lacked basic customer service skills and manners. To be frank, I have received better service at a fast-food drive-thru. This kind of service reflects poorly on your business, and I hope it will be addressed to prevent future negative customer experiences.