i did not say the problem is with you. The problem is with my provider and I found it really weird that they presented me with a certificated issued to them. (perhaps that's how it works!)

Sure you are aware that a browser string can be faked/changed. But how are you going to sanitise it so that you use it for checking uniqueness together with the IP, which in itself is not unique, i.e. a given hospital may have the same IP for all personnel trying to report something to you.