Is this legal and how would I go about pursuing legal action?

Wells Fargo shut my account down without warning because my parents accounts were being closed. I've had this account for three years before I was 18. It is linked with my parents joint account. However, I have a different account number and I have statements with my name and not theirs. I have maintained a positive balance in my checking account since it was opened and I make Wells Fargo credit card payments every month. This insensitive company left me stranded at the gas pump on my way home from college. I called knowing I had funds in my account which they would not release $30 of it for me to fill my car up with to get home claiming it was a business decision to close my account. They mailed me a check 15 business days after the fact with my mother and my name on the check and I could only get it cashed with her presence. Now I've been informed by mail that my credit card is being shut down because they were linked to my checking and savings account. I have suffered much anxiety and stress from this whole ordeal and do not understand how this business decision is legal.