+1(514) 937-9445 or Toll-free (Canada & US) +1 (888) 947-9445
I had an error the first time yesterday (with a message that said your transaction was not processed and no payment was deducted) - so I tried it the second time and it worked.

But this morning, I got an email with the receipt from the first transaction, so obviously the transaction had gone through! I really don't know how incompetent these guys are.

Again, I need to wait for 45+ min for an agent to come on the phone to ask for a refund (if I can even get through!).
 
I am on the same boat. I paid twice which did not go though last night.
I decided to make one more transaction and it went though

Wake up and saw two extra receipts in my email. I am on the queue now to see how I can get refund
 
Just talked with the agent. There is nothing that she can do. Here is the instruction via email

How do I ask for a refund if I paid my fees online or at a bank in Canada?
If you paid online or with a fee receipt form (IMM 5401), ask for a refund by emailing us at IPRMS-SIGPR@cic.gc.ca

In your email, include:

  • your name
  • your current address
  • the receipt number
  • the date of your payment
  • the amount you paid
  • the reason you want a refund
If you don’t have the receipt number, include the:

  • first four and last four numbers of the credit card used for payment
  • card expiration date
  • cardholder’s name
We may ask you for a copy of your credit card statement.

If you used a credit card or a prepaid card to pay, we will issue a refund to the same card. Keep it until the refund is complete to prevent delays. If your card is expired, we will issue a cheque instead.

If you paid using a fee receipt form (IMM 5401) or an Interac debit card, we will also issue a cheque.

Refunds can take up to eight weeks to process.

International Experience Canada (IEC) applicants: See refunds for IEC
 
other option is to dispute the charge from your credit card. I talked with my mastercard yesterday and they said they can dispute it as long as it posted.
 
Cic sent me the copy of the receipt for the one and only transaction I did . I wasn't expecting a reaponse so soon. I can apply today .
 
My charges are not posted yet but I asked my bank and they say they need the authorization number from CIC. I hope they do something to help us because many people have had the same problem.
 
They charged me 4 times, and it was for two applications as well so need $3780 refunded. Hope it doesn't take long but I'm not worried.
 
My payment went thru (next day) and I got my receipt. Hope this helps someone. Cheers!
 
So my choice is to wait 10 days for a Receipt.... or pay again and hope that CIC can refund the first one.

they will! we paid second time and it worked; now in process to refund the first one
 
They charged me 4 times, and it was for two applications as well so need $3780 refunded. Hope it doesn't take long but I'm not worried.

it's stressful if they don't do it fast; ya, i double checked and they confirmed they will refund but it could take up to 4 weeks; even without receipt, j with your name and cc info they can
I also had the same problem of paying twice 630$ (the first payment I thought it didn't work and I received the receipt 12 hours later..)

I just called them and they sent me an email with this link to get a reimbursement: http://www.cic.gc.ca/english/helpcentre/answer.asp?qnum=619&top=4

The only problem it will take up to 8 weeks and the interests of my credit card won't wait :(
in the confirmation of refund email it said up to 4 weeks
try to call your cc maybe they will give you a waiver?
good luck!