Usually in taiwan, customs is the choke point. It is rarely the logistics services post clearing the customs dogs and tax dogs.
You can bark back at the logistics companies, no issues. If you bark at customs, dont get emotional when your parcel gets burned, missing or returned to sender haha. Good rule to.follow, globally; though, taiwan is generally very good, especially compared to broken systems like in the USA, india, Philippines etc. The issue now is the ccp virus and the government dealing with a 3 way attack: china/chinese kmt sabotage, from the fact they want to protect people from the ccp virus/the absolute onslaught of mail orders due to shop closures (also due to ccp virus). be patient, they are still normally faster than most of the planet. In times like this, for domestic deliveries i suggest using post. Courriers are bogged down pretty bad these days