trouble shoot gd library

Hi, We are a hosting company set up whmcs on linux vps. The whmcs is working fine except showing verification image while submitting forms. We get the message like "Please enter the security code shown in the image - this is required to prevent automated submissions" The task is to check the proper installation of gd library (install/reinstall if not proper), compile with php and make the script work properly without error message mentioned above. You also need to give a brief document what you did to make it work. The budget is very very much under 30$ and you should be available to complete in a day's time. One of our system admin may interact with you while you work on the issue. Please bid only if you have worked on whmcs installation and trouble shooting.