You may have something here worthy of pursuit, but more info is needed. Use caution when chasing down customers.
The implied covenant of good faith and fair dealing is an inherent provision in every contract, even if not spelled out in writing. The covenant requires parties to act in good faith and act fairly when dealing with counter parties. Its violation arises when one party manufacturers the circumstances where the other party can do nothing but breach the agreement (the breaching party cannot perform until the other party acts first).
This argument may or may not be applicable directly to your circumstances, but it's worthy of further examination. The terms of contract which create the obligation to pay you need to be carefully reviewed to understand whether there is a no-fault failure to perform the obligation of paying you, and the facts should be further evaluated to determine whether your client used reasonable efforts in furtherance of the agreement, but the results didn't pan out creating no obligation to pay you.
Be advised that getting tough with customers has to be done diplomatically, as you could get a reputation as a person not-so-great to engage because of your inclination to bring lawsuits and dispute issues. A fair work-out with your client should be considered so as to extend the relationship and give you the opportunity to gain new business from the client, but payment-in-advance next time. Also, consider revising the conditions in your retainer agreement which give rise to your payment and retention of your retainer without recourse from your customers.
Your fact situation calls for a sit down with an attorney with you bringing your agreement, and the pertinent communications. The other side's position does not seem reasonable, but I would have to see the documents to provide an intelligent assessment.
In general, if a specific time is not specified, and time is not declared to be of the essence, the party obligated to undertake performance can do so within a reasonable time. How much time is reasonable depends on the particular circumstances.
Since you are in the Dallas area, you may wish to take advantage of my free hour of consultation for new clients. If you make an appointment, please bring copies of your pertinent paperwork.
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