Product: Student loan

I cosigned with my parents on a loan with Wells Fargo about 13 years ago as a student. I have made payments on time every month to the loan via direct debit ever since. Last year around XX/XX/2016, my parents filed for bankruptcy. In XX/XX/2016, Wells Fargo canceled my direct debits without notifying me. Three weeks after the payment had not been drafted for XX/XX/XXXX, I called to ask why they failed to take the payment. They informed me they could not take payments while the primary borrowers were going through bankruptcy, and that they were a not 'allowed ' to inform me of that. Nonetheless, I made two check payments in XX/XX/2016 when I spoke to the representative. One to make up for the XX/XX/2016 payment, and one for the upcoming XX/XX/2016 payment due in less than a week at that point in time. The representative assured me this would bring the account fully up to date. I knew they had drafted the XX/XX/2016 payment and it cleared my bank, so knowing that I was making the XX/XX/XXXX and XX/XX/XXXX payments ( before XX/XX/XXXX was even 30 days late ) I agreed that the account must be up to date as well. I set up auto-pay with my own bank to send checks from XX/XX/XXXX onward, since Wells Fargo said they could no longer take payments with their auto-pay system. 
What the representative failed to tell me when I spoke to her in XX/XX/XXXX, was that Wells Fargo had arbitrarily refunded me my XX/XX/2016 payment in the form of a check in early XX/XX/XXXX. They coded the check 'BK Overpayment ', and then considered XX/XX/XXXX payment unpaid. Had she notified me of this issue, I would have made an additional payment when I spoke to her to make up for the refunded payment, and would have waited with fingers crossed to see if their 'refund ' check ever came in. ( I did not receive the check until XX/XX/XXXX. Seeing that it was coded as an 'overpayment ', I wondered if the representative I 'd spoken to the month before had made an error in requesting I make two payments. I was confused, but trusted that it was just that - an overpayment - and deposited the check in XXXX XXXX. 
In XX/XX/2016, my father received a letter from Wells Fargo stating that the loan was past due. I never received any letters or correspondence from Wells Fargo - so this was the first time I heard of it. I called them in XX/XX/XXXX, and they finally informed me what the refund check really was - so I made an additional payment at that time to bring the account up to date. 
My credit report was flagged for four months of the loan being consecutively 30 days past due, from XX/XX/2016 - XX/XX/2016. This has caused me a lot of grief since I am currently going through an investigation to obtain a XXXX for a government job. I had to provide all bank statements, letters and evidence to the investigators to corroborate my story, it has caused months of delay of my being able to obtain the XXXX, and thus, be able to work. 
Furthermore, it is a blemish on my credit and will affect certainly affect future credit decisions. That loan has been paid for 13 consecutive years on time. 
I contacted Wells Fargo and opened a dispute against the negative credit reporting. They sent a letter stating that it appears the 'information they reported is accurate. ' I re-opened the dispute again. They sent the same letter stating the information is accurate. I will re-open the dispute a third time, but am afraid this will be an endless cycle. 
Given that I did my due diligence to rectify the situation when I spoke with the representative in XX/XX/XXXX ( before the payment was even 30 days late since that I caught that the XX/XX/XXXX payment had not drafted ), and given that the representative assured me the account was current in XX/XX/XXXX, and given they made no attempts to contact me until via my father in XX/XX/XXXX, it hardly seems fair I am being punished for a payment they arbitrarily refunded that I did n't receive until 3 months later.