I don't think that there is an another way to contact them. I think it really depends on the officers... I never got an answer either, I sent extra police certificates, and was asking if they had received it etc - and never got an answer. then one day - DM! so hopefully it will be the same for you - and you can always go to Canada on a tourist visa if you don't have the COPR by then. But 13th june is still almost 2 months away - so it should be enough to finalize your file, especially if the only thing they were asking for is the RPRF - it means that they most likely are finalising your file, and getting ready - maybe they just can't be bothered to answer, thinking "they'll see it soon enough on ecas" - that was my reasoning, hope it will be the same for you!
Good luck,
Sweden