Payoneer doesn't have option to dispute/chargeback.
Technically a user can file a chargeback up to 90 days (and even more) from when the charge was performed. These are usually issued directly to the credit card company and MasterCard would basically automatically charge it back to them. When we get notification, we will ask you for proof that the job was performed (though it's very hard to prove of course), but honestly there are very few cases where this is resolved.
To file a charge back on your card, you should contact support and they will provide you with a form to fill with all the relevant information: https://payoneer.custhelp.com/app/Contact_us