Maybe Globe had failed to inform you that when availing or recontracting fo another plan while retaining your number, the new contrract is usually applied after your usual cut-off period.
If for example your cut-off is every 10th of the month, the new plan would take effect on the 11th. Charges prior to that would be applied on your previous plan.
Before all hell breaks loose, I suggest you go to a business center (hotline would take a longer time to resolve) and tell them tht you were not informed about it so reversals or a compromise could be done.
It has been done in the past... Good luck.