We hired a pool designer/builder to complete the installation of a pool and backyard remodel design. We did not allow for sleeves to be in the contract, as we were unclear they were needed, however we did take this information back to the builder once discovered and they agreed via text message to install the said sleeves. They pured concrete without installing the sleeves and are now threatening a mechanics lien on the property due to non payment, as we are attempting to be compensated because we can not go back and place those sleeves as the concrete has been poured. Would the text message from the pool builder be legally binding in California?