eGo-c Twist 1100 defect

[Ileea]

I ordered a starter kit off Ebay with a basic cheap disposable tank and a charger. The battery seemed fine until I went to change the tank on it and the entire collar came off the cylinder of the battery. I was able to push it back on and if I am careful to only grasp the collar of the battery, where the button is, when I go to unscrew a tank we have no problems. It still charges and vapes just fine. The seller on ebay accused me of lying to him and breaking it in my pocket. I promise I did not. I have had it on a lanyard since it arrived last week. My question is what, if any, is the best way to fix this one or do I just say screw it, lesson learned, buy a new battery?