I totally get the "whack a mole" analogy, just don't put down the club yet! You did well with that account, sooner or later he will run out of options.
And if you can charge him for anything that he does fraudulently using your name, please have at it, girl! You will be glad you did in the end.
I'm cheering you on, soon or later you WILL whack that mole and be allowed to live in peace.
Hugs