Sometimes people WILL work for free/next to nothing though. Not to pat myself on the back or anything, b/c there are many people who are way more generous and giving than I am, but I have 2 families in hard times. One used to pay me on time always, never any problems, when dad lost his job and enrolled in school I agreed to keep the kids for less than half of what they had previously paid. Another family is a single mom,2 kids. She is allowed to bring her kids for free, whenever I have a spot-usually one full day a week for both, one other day for one of them. I know she is struggling and there is no way she could afford to pay anyone. I have enough families paying full tuition that I can pay my bills, though I am by no means rich!
I feel that I have been blessed through the years by so many people in so many different ways, and doing childcare is as much a callilng/mission in life as it is a job, and it is one way that I can "pay it forward" as the saying goes
I'm not sure there's anything you can do, since you don't have anything in writing, and she probably has your origingal contract with full payment terms listed. Sorry for your problems.