Complaint sub-issue: Trouble with how payments are handled

During redetermination of my income based repayment, I mailed in the redetermination form, a copy of my XXXX tax return and a copy of my driver 's license due to a recent name change. I am recently married and called the company to find out what to include, and was told that since we did not file a joint tax return that his return was not required. So, I mailed in my return, the form, and a copy of my ID. 
I then received a denial letter that they did not receive my tax return nor my husband 's. I am 100 % certain mine was in the envelope. I called the company to inquire as to where my confidential information may be and did not receive much of a response besides, it was n't included in the envelope - which it was. I was also told that I DO need to send my husband 's tax return ( misinformation ). 
Frustrated, and lacking other options, I comply. I print another copy of my XXXX off of my computer and a copy of his XXXX, and I include a short letter. I shove everything in the envelope, confirm everything with my husband - a second set of eyes - and mail the stuffed envelope. 
Today, I received a phone call about my written complaint, attempting to console me for the loss of my confidential information. During this call, the woman reviews the paperwork on file and tells me that they did not receive my husband 's tax return. Me, and him, both verified that this was included in the envelope, and Fedloan is requesting that I submit his tax return again ( I have an Income based repayment that does not include his income, regardless, unless we file married filing jointly-which we did not ). 
I am frustrated at the carelessness of handling confidential information. I was told on the phone today that they strictly shred documents after scanning, so, there are one of two scenarios. 
1 ) This company is scanning documents and experiencing technical issues - which should require employees to verify that documents are successfully scanned before shredding information 2 ) This company is employing careless employees who are either not properly scanning/reviewing the documents that are being received or they are stealing confidential documents. 
I had someone file a tax return in my name two years ago. I currently have a freeze on my credit report. All that someone needs is last year 's AGI, a social, name and address, and identities can be easily stolen. 
In a similar -mailed event issue- I somehow set up to receive paperless statements. Included in this must have been a document to re-determine my application several years ago. I never received this document and was unaware that renewal was due. It was n't until I received an email about a {$120.00} bill due that I was aware of what had happened. Because of this, my loan interest was compounded and added to my balance. Despite calling, I was told this is irreversible and that is not fair. I have since changed my settings to receive paper documents. 
I have also, in an effort to improve my credit, began making small payments on my loan ( my current payment amount is {$0.00} ). I found out that fedloan does not offer an option to apply a payment as a principal reduction. All online payments are being applied to interest only at this point, which is an extreme handicap to borrowers. 
This is an overall poorly managed company with little to no regard for the customers at its mercy.