I just looked at section 8 of the Provincial Offences Act. Basically if you settle out of court/plead guilty, it "constitutes the conviction." It does say to pay the set fine... but... I recalled some legislation from the Harris government imposing the victim surcharge. I looked it up, too, and the Victims' Bill of Rights was what they used. It pointed to section 60.1 of the Provincial Offences Act as the mechanism to collect it. S. 8 of the POA also says, in so many words, a guilty plea = conviction. Then section 60 talks about "fixed costs" (court costs), and section 60.1 talks about surcharges that are imposed on those convicted (victim surcharge). It does talk about imposing the surcharge after a "proceeding," but having done a brief search of the Act, it looks like a "proceeding" could be anything from settling out of court to actually being in court. ("Commencement of proceedings by certificate of offence.")
I'm no expert, but I think since they say the out-of-court settlement/guilty plea "constitutes the conviction," the additional costs/surcharge are legit, as is the total payable - if the amounts are correct. Poorly phrased and convoluted, regardless... That dog's breakfast is one of many reasons why I'm not a lawyer. Jeez.
Let us know your exact set fine and total payable. Then we can figure out how to go from there. But if one of them, or both of them, are in error, then yes, do not respond to the charge!