If you have not extended the contract, there is no contract. What was the execution date of the contract? In my area it takes about 45 days to close a transaction that involves financing.
Here is what I would do:
1. Consult with your attorney.
2. Have your realtor submit an extension of the contract amendment to the buyer's agenta asap.
3. IN the amendment, put time limits on when the buyer will order the survey if one is needed.
4. Put time limits and if you cannot negotiate reasonable limits, put the house back on the market.
5. In fact, I might just put the house back on the market to get a backup contract and go to the back up if the second contract closing date is not met.
I would never recommend that you not consult or use an attorney. In Texas that will get you out of the Real Estate with a suspended license quicker than anything. Consult a good attorney that is working for you as your agent.
I would bet that the buyer is having buyer's remorse and will not buy your house.
You need representation by a professional Realtor.
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