Product: Checking or savings account

This is a conflict between Citibank and XXXX XXXX XXXX, and I have been stuck in the middle with my money missing between the two. While XXXX has been helpful, Citibank has been evasive and uncooperative, and seems to not truly know what happened to the money. The story is as follows. 

During fall of XX/XX/XXXX, I received monthly rent checks from my roommate ( he banked with XXXX XXXX XXXX ). On XX/XX/XXXX, I tried to deposit a rent check for {$850.00} via my Citibank mobile app. After receiving an error message and no deposit confirmation, I took the check and deposited it physically to my XXXX XXXX account at a local ATM ( there are no Citibank ATMs in my state ). 

Six months later, in XX/XX/XXXX, I received a letter from XXXX XXXX noting a double deposit and stating that the funds had been corrected and sent back to the bank of issue ( XXXX ). This was the first time I was made aware that the check had been accepted by the Citibank mobile app and hence deposited twice. With this correction from XXXX XXXX, it seemed the problem had been resolved. 

However, a week later, I received a letter from Citibank also stating a double deposit and notifying me the funds there would be withdrawn on XX/XX/XXXX. This means both banks debited my separate accounts for {$850.00} ( total of {$1700.00} ). 

I contacted my former roommate ( now living in XXXX ) and he confirmed that yes, in XX/XX/XXXX his account was debited for {$850.00} twice but he hadn't noticed it then. However, he reports that on XX/XX/XXXX only one of those amounts of {$850.00} was returned to him. 

At this point I began working with XXXX XXXX XXXX to help understand the issue. 
A bank manager later confirmed that the {$850.00} returned to them and their member ( my roommate ) came from XXXX XXXX. XXXX  claims that they never received {$850.00} back from Citibank. Citibank, on the other hand, insisted that the money had been sent back. 

I put my Elevations contacts in touch with a Citibank manager so that the three could figure out the issue. However, email exchanges between the three became heated, with accusations flying of which bank had the money. After XX/XX/XXXX, all three stopped responding to my emails and calls asking for help with the issue. 

I continued to pursue the issue with Citibank, contacting multiple customer service representatives to try and find the proof Citibank claimed to have regarding the money being sent to Elevations. 

Finally, on XX/XX/XXXX, a Citibank research inquiry claimed that it found the transmittal number proving that the money was sent back ( they previously " couldn't find a transmittal number '' ). Citibank insisted that XXXX would need to fax them for this info. I was finally able to convince XXXX  to do so. But while they faxed a request for the transmittal number to Citibanks back office so they can locate the money, they have not heard back from Citibank. I am utterly disgusted by Citibank at this point. This issue should not have take over a year to be resolved. If Citibank truly has a transmittal number, it should be easy to share it with XXXX XXXX XXXX so XXXX  can reimburse me. If Citibank does not have a transmittal number, then they must have " lost '' the money or have it somewhere, in which case Citibank owes me the funds.