How many "minor changes" did your mother make?

Sorry to say but I am guessing she added a lot of shit to the work that they didn't feel was worth the original contract price or within the terms originally stated....I would have dropped the contract as well.

Take em to court all you want but my guess is that they wouldn't have dropped the contract if they weren't able to legally and I am sure it will hold up in court and cost your mother court costs as well.