I don’t know where you heard that, but the Justice of the Peace (JP) CAN reinstate the original speed. That means that that since your defence was set for the original speed, now you should ask for an extension to defend the new charge, which WILL be granted. Only the JP can amend the charge, not the prosecutor or the cop.
It hardly ever happens, and the one JP who does it (who is at the Newmarket courthouse I believe) is a serious d!ck. But it can happen. All you can do is ask for an extension.
PS the one guy it happened to was a punk ass kid who showed no respect to the court, or the court officers. He was mouthing off really badly. If you aren’t mouthing off, chances are it won’t happen. I’ve only seen it happen once in 9 years.
Next time, try to check out the relevant case law before making blanket statements.
www.magma.ca/~fyst is your friendly web site. Good advice for those not familiar with procedure, etc.
In the OP’s situation, request your trial date. If you show up and the cop shows up, then talk to the prosecutor and just plead guilty, as 15km/h over is a gift (as stated earlier.) If the cop is not there, then BAM you’re free.