Filing fee? I've never heard of this...
I always buy things from sellers that have at least 50 feedback and more than 98% positive. I've only had to file a dispute one time before, but I got a full refund.
If I don't get a full refund this time, I'll never use PayPal again with any type of cash. I'll only ever use it by paying with a Credit Card as I'll just go back to that company and get my credit... American Express has been very very good to me...
Mike