What's the deal with aCH payment reversed after goods shipped?

I publish illustrative scenarios prepared by my practice. All participants and conversations are fictional. The fictional posts are not posts by real users, accounts of client experiences, or reports of actual results.
Illustrative scenario prepared by my practice.
For informational purposes only. This is not legal advice. Laws vary by jurisdiction. Consult a qualified attorney for advice specific to your situation.
Hypothetical question

I'm dealing with a situation and need some guidance.

ACH payment reversed after goods shipped. I've been dealing with this for about 9 weeks now and teh situation isn't improving.

The amount being held/disputed is approximately $39,011. I have tried contacting their legal department 7 times with no resolution.

What are the risks if I pursue this? What's the likely timeline?