Battery Life Draining and also charges up to 100% but it shuts off after a while

My watch of 6 months old is losing battery life. It charges, shows that it charges to a 100% and then the power is completely drained after a few minutes.

Same cable, same plug point. We have been Garmin users for years but I will never purchase another one if this is the state of after sales service. The options granted to me by Garmin is that was that a refurbished watch will be given to me.

 Thats not a solution. Why does Garmin want to give me a second hand watch, without even troubleshooting the issue? I purchased the Garmin watch because I have never had a problem with Garmin. I dont want some watch with recycled parts. 
We purchase new watches knowing that it has been unused and of a good quality! This is highly unacceptable. 
Not sure if anyone else has this experience with Garmin?