eWAy Payment Gateway Missing After Update

I recently upgraded from PS 4.0.1 to 4.5.2, but the eWay and Sage Payment gateways are not available in the admin settings page. I can see there is an advanced folder with the PHP for the eWay gateway, but how do I get it into my store settings options? Do I have to copy the code and paste it somewhere? Did the update go wrong? There are a lot of duplicate files in various directories, so without following the code, I'm not exactly sure what code is being executed.

I have programming experience, but the structure of PS is still kind of cryptic. I need to be able to receive US funds and have them deposited in a Bank of New Zealand merchant account. My client has an eWay account and bank account in BNZ, but I can't figure out how to enable his gateway. PS settings still only shows PayPal and Authorize.net.

Please Help ASAP as we are ready to sell. I tried tech support and was told to post here for an answer...keeping my fingers crossed that someone will know.