Alas, for either the gentleman from Minnesota, or the chap who likes to solicit, it is indeed a terrible feeling to be told you have a deal and find out you don't. Any buyer's agent can sympathize with a buyer who has had that happen. But a seller's agent has only one duty, and that is to get the best deal for his client. There is the vaunted code of ethics that all Realtors are required to follow, if the said solicitor is a member of the highly esteemed Association of Realtors. Some choose not to join the syndicate.
A member of the public can always file an ethics complaint against a licensed realtor. And these can result in fines or even suspension. But, the first article in the Code of Ethics clearly states that a realtor's duty is to his client. So despite the disingenuous behavior, the soliciting estate agent was actually doing his job.
I was gutted after all the running aroung I did and found out that the seller did not have the courstesy of giving me a ring. The estate agent said they rang and left a voice message on my mobile but I did not recieve right up to today....
If in fact you have just made an "offer" and you do not have a signed binding "contract" with the Seller, then typically the Seller can consider any other offers. Anytime a Seller receives an offer, they can accept, reject, counter, or ignore the offer, even it is full price.
You might be in the middle of negotiating with the Seller, with only a couple of issues to work through, and another offer comes in, the Seller can drop you like a hot potato without giving you a chance to meet or beat the other offer.
In many states, even if you verbally agree to all terms with the seller, the agreement isn't legally binding unless it is in writing and signed by all parties, which is why Realtors want to get the agreement in writing ASAP.
If you DO have a binding contract with the seller, the seller can still market the home and negotiate backup offers, just in case you don't close the deal. Backup contracts are rare, as most contracts do close.
I you need a referral to a good Realtor in your area, let me know.
I assume that you meant that you already have a contract to purchase a home, and someone else has made another offer. Somebody else certainly may offer on the house, but the seller has contracted to sell the home to you. The seller certainly has the right to accept a backup offer. These are accepted and held in second place position in the event your deal falls apart.
Or, if the other offer is better than yours, the seller may try to find a way to cause your contract to fall out. For instance, when you go to make requests for repairs after the inspection, the seller may refuse to make any repairs in hopes that you back out.
I am a Realtor in SC and the customs and laws in NY may be different. You shoud really discuss this matter with your local Realtor.
Best of luck to you,