RMA php script or WordPress Plugin

I have been looking for a standalone RMA (Return Merchandise Authorization) php script or even a WordPress plugin. As much ecommerce that goes on, I was surprised to find that there are no plugin or scripts to deal with merchandise returns. Be great if someone could point me in the right direction.

which management software have you? (Magento…?)

No not magento, we already have a shopify store. we are looking for a stand alone php solution or a wordpress plugin. It would be great if it was a shopify app.

Oh shopify are beautiful…

Can i describe this extensionen accurate? (Serialnumber search? etc.)

Greez