funds in US dollars vs. Canadian dollars (CAD)

Hi, I am new here.

Mailed my FSW application to CIO couple weeks ago: no AOR yet, of course :-)

I've made a mistake, however:
I have included two US international postal money orders as my application fee, made to "Receiver General for Canada", 2x$550, but in US dollars instead of Canadian dollars!! It is actually a little more than 550CAD...

What is going to happen? I am hoping they'll just ask me to re-send the fee. What are the chances of our app being rejected right away because of that?

Another question is what is "Receiver General for Canada"? Does it mean anyone can intercept my mail and cash those money orders? Unfortunately, I am hesitant to use my credit card, as there was a security breach there last year, so I had to change numbers - cannot guarantee the same thing won't happen during 6 months they want me to keep $$ there...

thank you in advance for any info
respectfully, Igor