Trademark Dispute | client reselling my photography

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Illustrative scenario prepared by my practice.
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Hypothetical question

Yeah quick background on my situation — any input appreciated.

client reselling my photography. I've been dealing with this for about 9 months now and the situation isn't improving.

This involves software/code I developed over the past 17 months. I do have documentation proving my ownership and timeline.

Do I have a strong case? What should my next steps be?