MacBook air battery calibration not working

Hi,

I have recently purchased a MacBook air 13". I read that you have to calibrate the battery in order to get full battery capacity, and I have done so, twice. Yet, the battery is draining very fast, and the estimated time remaining goes from 20 hours to 3 in about thirty minutes, and when it says I have 3 percent left, it says I have seven hours left of battery life...

What can I do? Is this a serious issue that it is not calibrated?

Thanks so much for the help, I am a bit lost here.