If they don't offer you the proper spare at their expense, you can threaten to goto Omvic and complain they sold you a car with improper spare, and you don't know how they passed the cars safety with the improper spare. You can also complain to the MTO about this dealer selling you a car safety and certified with an improper spare but that might cause you more problems than good.
Although technically, any dealer can throw any "spare" tire in the trunk and get the safety done... Most people writing the safetys easily will "overlook" this.
I'm most curious which dealer you bought it from!
and I'll tell you how hard you'll have to fight for the proper spare!