it shouldn't just tear up... where do you keep it and how do you use it? maybe you're better off using it on battery more often than not or getting yourself a good lapdesk.
For some reason same thing happened to me too and the wires were exposed.
Why are you paying for it?! Take it to apple store and they'll give you a new one, at least that's what I did. They wanted to give me a refurbished one but couldn't find the right one among the refurbished ones so they gave me a brand new one to me, total cost to me 0.
You shouldn't be paying for replacements. This kind of thing is normally covered under warranty. It is product defective therefore should be replaced at Apple's cost.
P.S. I have had mine replaced TWICE due to similar problem.
Shop for your Apple, Mac, iPhone and other computer products on Amazon.
We are a participant in the Amazon Services LLC Associates Program, an affiliate program designed to provide a means for us to earn fees by linking to Amazon and affiliated sites.