Hi thanks for your purchase, actually the script files you are using they are not updated they are outdated.
Please update your script via FTP download new script files from codecanyon and then replace files on your sub domain except includes/db_contact.php . Once you do this the problem you are facing will be resolved.
If you don't know how to update via FTP send me your FTP or hosting logins i will make the update for you and if you already have done some type of changes in script files mention that so while replacing files you don't lose any customizations if you have done.
Once you complete the update the problem about your payments for vendors will be loading again nicely.