PASS charges a flat fee of 50 fils per transaction.

No, PASS charges a flat fee of 50 fils per transaction, not per hour.

The minimum amount required to enter a parking lot through PASS is a balance of 250 fils.

The PASS system will allow you to exit. However, your account will be disabled until you have credited your account again. Once your account is credited, the deficit amount will be immediately deducted.