A return request should have timed out by now, which I would think would also result in PayPal releasing any funds on hold, but I do know occasionally a request will drag on for a bit longer than they are supposed to - if the request has timed out, the only thing I can suggest is calling PayPal and alerting them to the case status (I'm guessing they must have some way of verifying the case status anyway, but sometimes they might need a stern nudge). 

I would be hesitant to contact eBay if the case hasn't timed out, just because with them you can never be sure they're understanding you, and I personally don't trust them enough not to just automatically escalate and refund the buyer. 

It might also depend on the reason for the request, i.e. if it was simply a change of mind or if the buyer claimed not as described, but realistically the buyer hasn't met the timeframes for either instance, so I think a call to PayPal is the best way to handle it.