Product: Checking or savings account

I opened a personal checking account with Citibank on XX/XX/XXXX online after receiving an offer in the mail. The account opened and I funded with a {$XXXX} deposit. Also added {$XXXX} from XXXX pay to this account. On XX/XX/XXXX I went to deposit an endorsed check via mobile deposit on the app. Received an email stating my deposit is being processed and I will get further information regarding that deposit at a later time. Went to login to my banking app and kept getting an error stating they are experiencing delays and could not get in. I later called the phone number on the back of my debit card to speak with someone about still not being able to login to my account. The automated system prompted me to enter my debit card number to locate my account. I entered it. Once I did that it immediately transferred me to a representative. They asked for my account number and I explained I just entered my debit card info through the automated system but she still proceeded to repeat the card number to confirm which account I am calling about. It felt sketchy but I still gave it to her. She then proceeded to tell me that my account has been blocked and I need to call another number to speak with the fraud dept. I called that number and they said the check deposit triggered a fraud alert and that my employer who issued the check needs to call and verify the check. So I gave my employer the phone number and instructed them to call to verify. Once my employer called, they asked my employer which account they are calling about. My employer provided my name but they needed more information so I handed my employer my debit card so they know which account. This alone is a red flag because if I was not there how would my employer have my account information? Their call center is based overseas so no one is here in XXXX. This makes it feel like its a scam because they don't even follow standard bank procedures. They asked him some questions and told him to tell me they would let me know in XXXX the status of the check. I did not get a single call/email/letter that my check was being held for fraud, that my account was blocked or anything. If I did not call to inquire about the strange message saying " our system is experiencing temporary delays. Please try again later '' I wouldn't have known anything. So here we are on XX/XX/XXXX I get an email stating there is a new letter posted to my account regarding funds availablity of the check. I can not get into the app to see this letter. On XX/XX/XXXX I received an email from them stating my account will be closed due to violation of terms per client account manual and if there are any funds I will receive a check after XXXX  days to the address on file but if I feel I should have the funds sooner to stop at a local branch. On XX/XX/XXXX I received an email stating that my check has been accepted. After all the confusion I decided to stop at my local branch to figure out what was going on. I went to CitiBank at XXXX XXXX XXXX XXXX, XXXX XXXXXXXX XXXX XXXXXXXX on XX/XX/XXXX, they called the XXXX department and were told that the check I deposited violated the terms and my account will be closed and there is nothing that can be done to reverse it. I asked about the funds in my account besides the check that was deposited and they refused to give me any of my money. My employer also stated the check was showing cleared on his end. The are holding my money and not giving me a clear reason why. I have a pending tax refund being deposited into that account as well which will now be rejected and cause me further financial burdens/delays.