Thanks for posting in the PayPal Community forums for help with this issue. I'm sorry to hear that you may have made a payment to PayPal Credit for the wrong amount. That is understandably frustrating. If you submitted a payment for more than what you have in your PayPal balance, it is likely that the payment will actually come from your bank if you have a linked bank account.
If that's the case, you may need to contact PayPal Credit directly to see if they can refund part of the payment towards your PayPal Credit balance. Near the bottom of this page, you can find PayPal Credit's contact information.