When you're out of plan data and are in FAP (throttled), purchasing token data brings you back out of FAP, and you're then no longer throttled. But, your service speed will still be subject to load and congestion, just as it would be when using plan data.
Basically, token data is like gasoline in a reserve gas tank. If you use up the gas in the regular tank in a truck, the truck then switches to using the gas in the reserve tank. Though it's "reserve" gas, it's still gas and used just like the gas in the regular tank. IOW, token data is just like service plan data, but when it's used is what's different. Token data also has it's own "data bank" because, unlike your plan or bonus data, token data rolls over. You keep what you haven't used.
I don't have the mobile app available to me right now (my phone's battery is dead), but it should be showing something that indicates you're drawing from your token data, and if you are out of plan data and you do have token data, your token data is definitely being used.
With regard to the token data purchases, there's no way to undo them, unfortunately. And I know with multiple purchases at $30 a pop, that's going to add up.
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