My Macbook Air's battery exploded. What can I do?

As you can see, my MBA (I think a mid-2013)'s battery got puffed. This was my spare laptop which I had kept above my bookshelf in case my main failed and this expanded and the laptop seemed stuffy. So I opened it up with a screw driver and removed the battery. It looks like just one portion is expanded.

1. Is there any service/program by which I can get Apple to fix this for me free of cost? (this is obviously out of warranty but I'm curious in case of battery expanding such as this).
2. If Apple can't help, is there anyway I can just change that portion of the battery that got puffed alone rather than the whole set? (I see there are full replacement batteries on Amazon but if I can save money I'd rather replace just the damage).