Do you have any documentation signed or otherwise, with her agreeing on the work to be done and the price to be charged? Or even return emails stating her acknowledgment and/or agreements?
Having learned from the "School of Hard Knocks", I bill ahead for monthly maintenance and clients get cut off, if they don't pay by the end of the grace period along with getting charged a 'late" and even "later" fee. Service agreements do alot to stop these type of issues BEFORE they even start.
Some future suggestions, with each agreed upon extra service, write out the estimate and that, becomes the work order when they sign and agree to it. Then they sign again when the job is completed satisfactorily and I've collected my payment.
I decide how I run my business and how I am to be paid. You need to make some changes asap. Besides, unless you're getting paid to extend credit there is no reason to "Float" anyone that long. Not waiting up to 4-6 weeks for completed work really helps with cash flow. Now, End of Lecture.
You get the point. I understand, "The horse has already left the barn".
So, how are you able to document to an uninvolved party, the dates visited and the work that was done? Do you have proof that you were there and the work discussed was done? Start gathering it up right now along with getting written statements from employees etc. Seems now you're gonna have to put even more man hours and work into this to possibly get paid. Good luck.