Is that correct? My only two options are to auto top up when my balance falls below $2.50 (I think it was) or an auto set amount top up each month? The trouble is if I use less than $20 a month the set amount one is no good, and if an auto-renew hasn't enough funds, but there is still more than the minimum amount in my account to trigger an auto top up, the auto-renew will fail.