If you under-/overestimated the customs value of your shipment, the calculation of taxes and duties provided by Easyship for your parcel will be incorrect.
Therefore, you should cancel your shipment and create a new one with the correct customs value.
If you underestimated your item's customs value, and it is being held by customs due to the undervaluation, then customs will have to reevaluate the taxes and duties for your shipment.
Remember to ALWAYS input the right value of the item as the customs value.
This value represents the Transactional value of your items.
Meaning that the amount your customer paid to receive the items.
If you enter a value that is lower than the actual one, additional fees may be charged to your account. This is also considered an illegal practice in many countries around the world and may lead to your parcel being held at customs or confiscated.
In many cases you may be required to provide proof of purchase to the customs officer.
This is a practice that happens not only for miss declared parcels but in general as customs officers do random checks of shipments.