There is not any practical way to do this effectively. There are several, rather tedious and incomplete, hacks that you can apply to attempt to prevent billabl

There is not any practical way to do this effectively. There are several, rather tedious and incomplete, hacks that you can apply to attempt to prevent billable actions after limits are hit. But to be frank - they're cop-outs for a real spending cap. You'd hope these companies would address this themselves - but it's not profitable for them to resolve (it's somewhat involved and requires them to allow people to pay them less)... So my strong vote is to make the contracts that allow this sort of "un-cappable" spending for automated actions void in court.