Researching about chargebacks the only place mentioned in their FAQ is this.
What I do if I send money to the wrong person?
You need to get in contact with your financial institution and make a claim. Your institution will help you to recover your money by way of a good faith collection effort, but it is not responsible of recuperating the money you sent by mistake.
What I do if I send the wrong amount?
If you transfer an incorrect amount of money, you need to get in touch with the person you sent it so you can get the amount you sent in error. We're not responsible to recover the money you sent by mistake.
My take is that it is very difficult to make a chargeback, basically they're saying : "you're on your own"
Another detail is that the maximum daily transfer per card / account is $500.
I hope this helps.