Hi @ERIN123, sorry to hear you hit an issue with our plans. Our smallest data allowance currently is a 5GB plan, but it is boosted by 1GB when this limit is exceeded, at a cost of $10. After this happens three times, additional boosts are barred. We send through a usage notification at 50%, 85% and 100% of used data allowance.
Many devices also allow you to add data allowance limits, to ensure that data usage is blocked once they hit a certain point that you specify, so this can be a good option for preventing children from exceeding the data cap.