Citibank Bank Account Or Service Complaint

Citibank Bank account or service department,

Checking account Account opening, closing, or management Texas

I opened a checking account with Citibank on -/-/- through a promotion which was supposed to pay me a $400.00 bonus. I should have received the bonus on -/-/-. I have yet to receive the bonus. I called Citibank customer service on -/-/- to resolve the issue, and was told they were opening an internal investigation to resolve the issue within 10 days. I have not heard back from them since, nor have I received my $400.00 bonus.