which scale to get is mine accurate?

I need a scale that reads over 300 accurately i still have weight too loose and I bought a taylor scale it goes up to 600. It worded perfect for the first few months now everytime you get on it for the first time it says error.. 6.4 pounds and I also weighted my self got off weighted again waited 10 minutes and third time adn they where all different the last by over a pound and a half. i was just wondering if this is typical or is mine just broke... and if it is what is a reliable brand i dont want to be buying scales every 2 months.

THanks everyone