I have created 2 new Apex classes and several VF pages to deploy to our production environment. These are needed for our Go-Live on January 22 but I am not able to deploy for further UX testing because Salesforce is complaining that our code coverage is only 59% on deployment from Sandbox. When I run the test in "Setup>Apex Text Execution" it says our Code Coverage is 79%.

I am currently doing a full run of all Apex Test classes, it's currently at 550/2758 with 39 failures. We use a managed application called PatronManager, but I'm not sure if managed packages and their unit tests are the culprit in this. Am I missing something?