Discover Consumer Loan Complaint

Discover Consumer Loan department,

Installment loan Managing the loan or lease Ohio

I paid my discover loan payment ontime as usual as confirmed by looking at my credit history I paid - -/-/16 it is confimred by an email from Discover stating they received my payment, I also received a confirmtion number, and I have proof from my bank and a copy of the bank statement showing that discover took the - out of my account on -/-/16 The payment was never applied to my account,, I called and they said there was a system update that caused problems with payments, the money was never applied to my loan, now I am receiving collection calls, and collection letters,, even though they said they will fix the problem they have not,, I faxed a letter to them on -/-/16 to the fax number I called and got from a Loan Manager, they have not replied or acknowledged they received it.. I sent copies of all the proof that the loan payment was paid, including the bank statement. This is now affecting my credit. I pay every month on time all my bills, now I am showing past due..I am so upset about this because there is nothing I can do about it. They will not correct the issue.. I have spent hours trying to correct this, I have done everything to correct this I have documents showing that the payment was made, and not just the payment but - over,, I like to pay over the amount due. What can I do? my hands are tied.. I am now going to have poor credit. How do I make another payment, It will be due again in a few weeks, how do I make the payment and make sure its applied to my account. If having proof, a cofirmation number, a dopy of the bank statement showing that the paymnet was paid to Discover, a copy of the email and these things do not correct the problem what do I do??