Postnet overnight parcel sending service useless

I have for the second time this year sent a parcel overnight express with Postnet, and for the second time, they do not deliver as per promise. This is now 3 days later. Trying to phone their customer care line is just as useless as sending a parcel with them. Their online tracking system is equally useless and do not get updated for days either! This has cost me money every time!! I will NEVER use Postnet again.