You may be able to cancel a recently made payment online by clicking into your personal loan on your dashboard, click "One-Time Payments."
From here, you can view recently scheduled payments, and cancel these payments by pressing the 'X' next to that payment. You are also able to cancel your Autopay by clicking into your loan and selecting 'Manage Autopay.'
Please note that Autopay must be canceled a full 24 hours in advance to prevent the payment from processing.