Why they have installed patch of enterprise edition?
Ask them to revert the patches if you want, and then check payment methods are working or not. If then works then either follow this blog post for the patch installation
or contact us, we will be happy to help you out with the patch installation for your Magento store for FREE.
SECURITY DISCLAIMER: The above website contains Magento Security Patch files which are self-hosted by the user and as such unsafe. Magento Forum advise all users to only download patch files from the official Magento Downloads page.
Magento.Stackexchange answer for applying patches without SSH => Critical Reminder: Download and install Magento security patches. (FTP with no SSH access)