Quote from a guy who PM'd me.
"You need to go to the Dubai Police General Headquarters. It's right next to Al Qiyadah metro station. It's on the same side of the road, right next to the station. It's best to go early in the morning to be honest. I doubt they'd be able to print anything straight away but they might. You need a passport sized photo to go on the certificate and your emirates id/passport copy, usual stuff."
Sounds like there are 2 ways of getting one, the above way.... and the way I did it (online).
The above way gets you a hard copy which is what Procius want. My way got me a PDF which Procius don't want. Even though its basically the exact same form! They are useless, I have my Airline looking into it and they also explain that Procius are useless. They say a PDF should be accepted as its a document that can't be changed (the whole point of a PDF).
I went into HQ the other day with a few questions. Regarding Proof of service letter... we get that on the last day in office from the EOS counter. Actually the lady Ive met there both times has been extremely helpful.