I had the similar situation in 2008 when I was preparing for a move from KSA to Canada.. I approached Saudi Traffic Police Dept ( licence issuing authority ) for getting a certification of my driving experience. The Captain ( he is the brother of my Saudi college ) gave me a computer print out showing my current licence history which contains date of issue and validity, on a plain printer paper, in Arabic. I requested it on the official letter head but the Captain said they are not authorized to issue any kind of such letter or certification. He told me to go to the Ministry of Transport office (MOT) at Malaz, Riyadh.. I went to MOT office and one officer told me to go to Ministry of Foreign affairs and get approval from there. Even though I was working in the Ministry of Civil Aviation ( MODA ) and I had some known people in other Ministries, I tried my best, but it was not successful. Several days I went one of my close Saudi friend to meet many officers but it was a waste of time. Most of them are saying why not Canada Government accept the Saudi Licence. What I can tell to them!!. With my driving experience for more than 20 years in KSA, finally I had to appear for Ontario driver's written test and road tests starting from G1, G2 and G accordingly..
However, may be situation changed now, and therefore try with KSA Traffic Police.