Worst customer service - pathetic

Worst customer service ever!!! Log a call Monday, 22 April because a package was not delivered even though the tracking status shows delivered. 2 people put the phone down in my ear already, followed up and followed up but no one is resolving my issue. Was told i need to phone from the same number everytime in order for them to help me but yet i give my tracking number.....how does that work??? So if i am not at work i cannot follow up using my cellphone because i have to phone from the same landline which means if i am off sick i need to wait until i get back to work to follow up....??????