Please use the track and trace service of the post office. And you may also contact Customs officials at the post office.

Contact point
Customs service sites in the post office
1.Kaohsiung Mail Processing Center Post Office(Kaohsiung Branch 92)
  Address: 7F, No. 853, Minzu 1st Rd., Zuoying Dist., Kaohsiung 81301,Taiwan (R.O.C.)
  Tel: 07- 3479316
2.Tainan Chenggong Road Post Office(Tainan Branch 901)
  Address: 5F, No. 8, Chenggong Rd., North Dist., Tainan 704401, Taiwan (R.O.C.) 
  Tel: 06-2222077