Your situation doesn't sound promising. Since you submitted your offer Thursday, the seller's agent would have notified your agent if it was your offer that was submitted. And I would like to think that your agent would have immediately notified you. I find it odd that your agent wouldn't answer your calls, especially since you have an offer on a property.
You mentioned the bank....was this a short sale? If it is....you've got a chance. Even if the seller accepted another offer, it is the lender/bank who makes the final decision. As such, if your offer wasn't accepted by the seller, you can re-submit another offer, and make it your best and highest offer. The listing agent is DUTY-bound to present your offer, especially if it's better than the first one.
Do note, however, that if ANOTHER and BETTER offer is submitted after yours, the lender may override the seller's decision, and accept the offer that is financially the best for the lender.
Finally....if this is a short sale, it takes 45 days or longer, from the time that the seller accepts, before the lender accepts, rejects, or counter offers.