Seller wants me to resolve problem but he hasnt fulfill the order

[444Excursion]

As the tile says...

I have a case with a seller.

At the moment he is working on the the completion of my order. (supposedly)

He wants me to resolve the case on Paypal before I receive the missing parts.

Is having a case open blocking something for the seller?

If I close this case would I be able to open another one  on the same transaction?

I don't feel it!

What is the right thing to do?