Most likely UPS costs are the brokerage fees and the dealing with the paperwork. If you don't want the items then let UPS know to return to sender. UPS will most likely refuse due to the extra costs and the additional work on the shipment. Then tell them to please destroy shipment but you will still owe them for the broker fees. Catch 22
The change to 30 days is not set in stone..so right now 60 days ..Thailand will now waffle between the change to 30 days from 60 days till announced in the Royal gazette.