Problem caused by your funds being low: Checking or savings account

Chime shut down my account with out notice, I contact them on several occasions, first they told me in will be restored in 48 hours, that didnt happen, then two days later they told me 72 hours, they keep telling me it was fraudulent activity on my, which I know is untrue, as long as I had this account I never had a problem, they told me they dont know the date of the activity, I ask them what was the fraud and they tell me they dont know, now they will not let me be able to do any other account, I am just confused right now, there was no fraud, I noticed as soon as I connected My credit card to that account thats when everything started going crazy, I couldnt pay for medication food bills or nothing,