Someone said it perfectly earlier. Don't go into these places loud and bolshy, just walk confidently in, smile at the receptionist and give her your details. I always try and be sympathetic to them if they're busy, it's all about the attitude you give them... BUT in the same respect if you think you've been spoken to wrongly or treated badly and if your not the type to cause a confrontation then when you go home ring in and ask for the reception/office manager and explain your problem. Make a bulleted list keeping it short and sweet of your complaint and hopefully have the name of the person who was disrespectful. Also let them know your time frame of when your expecting a response to your complaint, you don't have to say "so i want to hear back from you tomorrow" just let them realise that you will expect a response preferably in writing....
I hope it goes well for you next time xx