Without knowing the specific terms of the retainer agreement only a general answer is possible. The firm is responsible for the scope of work agreed to in the retainer agreement. If the firm does not complete the work, then the firm is liable for their default. This means that the firm could be sued for the cost you incurred to complete the estate work. The firm is responsible to complete the work even if the firm underbid the amount of work.
Send a letter demanding that the firm complete the work and request that they send a letter committing to do so. If the firm does not do so, you may have to get another attorney, but you may also have the right to sue the firm for its default.
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