Product: Money transfer, virtual currency, or money service

COMPLAINT ON BANK OF AMERICA CASE NUMBER -XXXX  I am writing to file a complaint against the bank of America on a transaction that was made to my account by my brother. On the XX/XX/2019, my brother made a transfer from his bank of America account to my Bank of America account in the same city in California. My brother made a first transaction of {$5000.00} to my account and on the same day transferred {$20000.00} to my account. The {$5000.00} was released but {$20000.00} is still held by the bank. 
This started on the XX/XX/2019 at about XXXX XXXX, I got a call from an unknown number requesting to know about the details from a bank transaction on the sum of {$20000.00}. I declined giving information to an anonymous person and suggested that I would go to the bank immediately to respond to the questions regarding my account. On my way to work and to the bank I got a mail from bank of America stating that my account balance was below {$25.00}. On getting to the bank I made explanations to the bank associate that the amount in question- the {$20000.00} was transferred to me by my eldest brother who lives in XXXX XXXX whom I loaned my me to give him an equivalent of the {$20000.00} dollars in naira ( XXXX Currency ) for a building project that he was working on in XXXX . I  explained to the bank associate that I had made the transaction to my brother and that was the reason I had the {$20000.00}. After the explanations, I was told that the back end ( the investigation section ) of the bank had closed my account and frozen my balance and I wasnt given a reason as to why that was done. I made an appointment with an associate, ( XXXX XXXX in XXXX XXXX, XXXX, where I opened the account and I showed her legal documents ( my XXXX XXXX   Statement ) and proof that the source of the money from my XXXX account was from a Call deposit investment from my childrens education insurance from my late husband. The documents I took to Bank of America showed the transfer of the Naira transfer ( herein attached ) that I made to my brother. The equivalency of the sum of {$20000.00} later paid to me by my brother. I also showed the associate a letter of attestation that my brother had written confirming that he had sent the {$20000.00} to me because i gave him an equivalent of the amount he sent to me. 
I made several attempts to reach the bank to understand why my account was frozen. 
On the XX/XX/2019, I got a mail from the bank stating that my account was closed, and the bank wouldnt release the remaining balance to me. After several calls to the bank literally every day, I got a cheque of {$5000.00} from Bank of America and upon receipt of the cheque I called the bank to make inquiries as to the status of the remaining {$20000.00} dollars but the response I got from the bank was that my account was under review and I needed to call back consistently to get a feedback on the status of my account. 
On the Ist of XX/XX/2019, I got another letter from Bank of America stating again that my account was closed, and there was no mention regarding the status of the withheld {$20000.00}. Again, I made several attempts to get a clarification from BOA on the status of the money and on the XX/XX/2019, the associate with whom I spoke with told me that the review on my account was concluded and the bank had decided to return the money in my account to the sender of the money. The sender of the money as much I know was my brother and in several discussions with him he has stated clearly that he hasnt received any money. In my several calls to the bank, one of the associates in the bank made a statement that someone called and made a complaint on the {$20000.00} transaction but the bank hasnt given any information regarding any third claim on the money in my account. I went with my brother to the bank to make clarifications to whom the money was returned to and we were told that my money was sent to a 3rd party that I know nothing of. 
I have requested on several occasions for the bank to give a written explanation on the reasons for closing my account and seizing my money and returning my money to the 3rd party. The bank has refused on several accounts to give a formal explanation to the status of my funds or to release my {$20000.00} to me. 
I hereby approach your esteem organization for the following answers : 1.Can the BOA lawfully seize/confiscate my money without due process or notification? 
2.Can the BOA arbitrarily transfer cleared funds ( the sum of {$20000.00} ) in my account to a third party ; without my due authorization or without a properly executed court order? 
3. Even if the BOA had based the seizure of my money on SAR /fraud regulations, is the BOAs action fully compliant with the constitution and in accordance with Federal laws? 
4.Also why did BOA not consider my explanation ( supported by Banks records and attestation from my brother ) as to the source of the funds? 

Please find attached all supporting documents to my complaints and claims and I will be happy to provide any document or information that will help resolve this issue.