My son took out a student loan from XXXX XXXX Bank XX/XX/XXXX. He was attending XXXX University in Ohio. XXXX then sold it to American Education Services. I am the co-signer of that loan. XX/XX/XXXX I received a letter from AES stating that the loan was delinquent and to bring the loan current I would need to submit {$120.00}. I sent the payment in on XXXX. The check was cashed on XXXX XXXX. XXXX was only working 1 to 2 days a week XXXX in XXXX, Ohio. He tried to get a deferment. We never heard from them. I never got a delinquent notice since XXXX. In XXXX I get a collection agency calling me. So I called AES XX/XX/XXXX, spoke with XXXX # XXXX. He told me that he could not get a deferment because the loan was in default as of XXXX XXXX or XXXX. I asked him how that could be because sent in the payment in XXXX to bring the loan current. He said it was in default because XXXX and XXXX payments were not made. I asked him why I was only billed for XXXX. He stated that they only bill for current month. So they took my payment and defaulted the loan anyways. The loan was sold to XXXX XXXX in XXXX ( XXXX ). They would not accept a payment plan. They would only accept full payment of XXXX. A lawyer advised us to make a payment to bring the loan current. On XXXX XXXX, I sent AES a {$700.00} check. This was the only address that I had. The check was cashed on XXXX XXXX. I called AES and they told me that they would forward it to XXXX XXXX in 45 days. Never heard another word from them. Now we get a letter from XXXX XXXX XXXX XXXX XXXX XXXX, XXXX. My complaint is with AES that as a co-signer there was no notifications. If I would of known that the XXXX and XXXX payment was dueI would of payed it. Now we are in this mess. I would like to file a complaint against AES.