For what it's worth: I created an account to try it out in January, played a bit with a cheap instance, and deleted the instance. Got billed in February (about 1€) while there was strictly no activity going on. Got to wait until end of March for the account to close, and with everything turned off I can see another bill coming in for 0.50€. Cannot remove my credit card details. Don't care much about the undue handful of euros, but I would not trust them for billing.