While attempting to make my student loan payment

1/16/13 – While attempting to make my student loan payment for the month of January, 2013 in the amount of $276.06 I unwittingly posted a payment for twice the amount ($552.12) through their 1-click payment option. After seeing this I immediately called and spoke to a representative (8:57AM EST – 25 minutes). During the call the representative posted a new payment in the correct amount of $276.06 and assured me that the $552.12 payment would be cancelled. Later that afternoon, upon seeing both amounts still pending, I called back (5:16PM EST – 12 minutes) and was again assured that the payment of $552.12 would be stopped. 1/17/13 – Both payments, totaling $828.18 are withdrawn from my account resulting in an overdraft. 1/18/13 – I speak with several representatives of Sallie Mae and they inform me a refund cannot be performed before end of business day Tuesday, January the 22nd, and so I will be left with negative funds in my bank account for 6 days.