Seller refusing to sign release during contingency period

[Jacquice Davis]

Hi all. I had an offer accepted on a parcel of land and sent my earnest money deposit to my title company. My agent built in a 45-day feasibility study contingency period into the contract. Two days after we were under contract, I went to a builder. They were already familiar with the land. Apparently, someone else who was previously going to buy that parcel went to the same builders and they determined that the actual usable land is significantly less acreage than what is advertised. And the house I'd want to build on the land is too big for what is allowed on the land. Therefore, I want to back out of the contract.

I signed the contract release, my agent sent it to the seller agent, and they immediately put it back on the MLS and it's now showing as active. Without sending back their portion of the signed contract release. My agent has been engaging the seller agent trying to get the release back. They asked for 'proof' of the feasibility study (which, my agent said: they don't need proof because we are within our contingency period). We gave them 'proof' via a recap of our conversation/visit with the builder. The seller (not the agent representing them) then sent a pretty nasty email to her agent basically saying 'please stop emailing me about this'. Their agent forwarded it my agent, who forwarded it to us. Now, my agent has threatened to contact the Real Estate Commission Board and we are filing a complaint.

This is happening in Prince George's County, MD. The person selling the land is a real estate agent (for reference).

I am just wondering how common this is. Refusing to sign a contract release within a contingency period...re-listing something as active before giving the contract release back to the the would-be buyer? And anyone have any other advice? 

Thanks