Pheal

Can anyone help? Just moved and the previous owner had a security system fitted with a Videoteknika G-TEK GT704TVI DVR. I do not want to pay the silly money for a maintenance contract that consists only a once yearly clean of the outside cameras that the installation company are looking to charge to continue the contract! The maintenance company have given me a User login/password but refuse to give me the admin login/password as it would 'compromise all their other clients'. They will not even remotely log in and reset the password to something like 123456 so that I can access it and reset to something else. So, despite owning a 4 camera DVR I am unable to do anything remotely interesting with it and now faced with throwing a perfectly good piece of kit away. Does anyone know this piece of kit and is there a way to reset the admin password (or add a new admin user)? Many thanks