Paypal — paypal not customer friendly. duping customers

I have purchased a t-shirt using paypal cash, but the shirt didn't fit properly, so i returned it. The cash got returned to paypal, but paypal is refusing to let me use this money because it was returned after the expiry date. I had returned the t-shirt as soon as i got it, but the return was credited after the expiry date. How am i supposed to use it before it got returned to my account? The vendor stated that the full amount would be refunded. It was not mentioned on vendor t&c on paypal site or vendor site, that i would not get my money back. At least 1 week grace period should be given to the customer to use that amount, if not full amount. This is like duping customers. I have never seen any good sites like amazon etc doing this.
While purchasing or returning product give warning on vendor t&c itself, instead of hiding this t&c somewhere
Please give me a 1-week grace period.