Create a user Policy on the logon domain, so if they delete your access, it comes back within an hour and a half.I would take a stance that if they don't want you on their machine consider them as not supported and go work with the user population that arn't mucking you about.
In some countries it is against the law to force yourself into a users admin group, be careful that you are working within the law of what ever country these machines reside.
