Capital One 360 Checking Capital One 360 Checking Account frozen McLean Virginia

I opened a Capital One 360  checking account on Aug.24,2017. On Sept. 6 I deposited $300 cash into the account. On the morning of Sept.7th I received a enail stating my account had been frozen and needed to call . I called right away and have called over 20 times now in 2 days.All I get is voice mail, so I keep leaving a message. No one has called me back. i went into a branch office and they could not help me. So now my money is being held captive and no one can tell me why or for how long ! I am a older man, handicapped and on a fixed income. This is every penny I own. Please help !