What the others have said. Once you put oil and gas in it you own it, they can't take it back and resell it as a new unit.
I work for an outdoor power equipment distributor, we run into this all the time with the box stores.Once they take it back in exchange they become the second owner and factory warranty will not cover the product. They should either repair it and submit a warranty claim or send it to an authorized service center on your behalf.
If you are unhappy with the noise level that is too bad, you should have done your homework. A reputable outdoor power equipment dealer would go through that with you before purchase. However they don't sell 300 dollar generators so the choice is yours.
