I was in same situation. They send whole bag back, like “missing payment”.A lot of people accidentally pay 100$ instead of the 255, its a very common mistake.
Your best bet is that CRA will only send back your OWP package instead of both PR and OWP. This happened to me and it saved me a lot of hassle. They include a letter saying what you have done wrong, so correct it, resend the package. *Double check for updated forms*. Must add that my package got sent back for a missing signature and not incorrect payment.