Please keep in mind that the Buyer is possibly excited about purchasing your home. Yes, it is still yours, but they may need to measure a wall, etc. Try to keep everyone moving forward to the closing date.
You also have a contract that probably states that the seller has to make the property available to the buy upon reasonable notice. Call your Realtor and see what happened, likely the buyer's agent had permission from your agent.
Clearly you feel violated knowing someone has entered your home without your prior knowledge. No one likes it when this situation occurs, especially the real estate professional.
Unfortunately, I have arrived at the front door of a home for sale that was scheduled to show the previous day. I ring the bell, knock on the door and proceed to use the electronic key to unlock the door. The owner, fresh from the shower, opens the door first. Yep, the arrangements made via the 'Showing Central' command center did not get to this person, who was the owner. Had they not been home, or worse, did not hear my knock or the door bell, I would have been standing in the middle of the home as they streaked to the dressing station.
Often, in the showing instructions portion of the listing, an agent will state, "Easy show, courtesy call before showing." This is interpreted as the buyer agent is to call the listing agent (or whoever is identified in these instructions) with intended time to show, and unless instructed differently by the listing agent, it's good to go and show.
There is so much we do not know pertaining to your specific situation. You may have a limited service listing agreement. You may have agreed to show the home yourself. You may have requested to be the showing scheduler. The status of your home may not be current and still shows as 'Active."
Finally, as you have read many times right here on Trulia, buyers do not like looking at a home while the owner is present. The are inhibited from having a real discussion regarding any issues or renovations, sensitive to offending the owner who has invested so much in their home. As primarily a listing agent, I keep protocols in place to assure absolute control of access to a home that has an accepted offer in place.
There is much we don't know, but we all appreciate how you feel and agree this is most unfortunate. There is much, however, that we do not know. Before you choose the "scorched earth" path, and escalate this, take a minute to see how things went wrong. Have assumptions been made? Is it possible you are over reacting? Then, rather than pursuing retribution, implement better controls.
Best of success in selling your AZ home.
Before taking action.....check your agent portion of the MLS information. Showing instructions should be indicated and clarify what the terms and expectations are for agents to enter your home. We always recommend that a home occupied by the owner before being seen has the showing agent be in direct/indirect contact with the owner.
Be clear on what your MLS states prior to contacting the agent's broker.....
What does your listing agreement and the MLS Listing state?. Does it say that buyer's agents need to make an appointment with you before they come in to your home? If it states they must make an appointment then you can talk to the Broker for the Buyer's Agent. What does your listing agent have to say about the matter?
The listing agent should be addressing the issue for you because LA works for you. But you can also talk to the Buyer's Agent Broker and make them aware of the situation.
Cara J. Simmons, REALTOR
ABR, CRS, CSSPE, EPRO, SRES
RRC - Referral & Relocation Certified
Sun Canyon Realty - Southeast Valley