I think your getting very good advice here by almost everyone. Return the shoes and request your refund...in full. you can't have it both ways, it has to be done in that order. Also, nobody mentioned your credit card co.?
You can get a charge-back for your purchase the same as any other buyer. Payment thru Paypal is through your credit card. You may also better complain to your credit card co. with the # on the back of your cc card.
It doesn't really matter what restrictions she put in the listing, even 'as is' or 'all sales final'...whatever.
The fact is that even with these legal quotes there is still another better one in your favor under the 'Fair Trades Act' called "IMPLIED WARRANTY". Al;so reconized in almost all states as well as CA.
So, do what you will, but I have to fully agree, Send the shoes back.