Delta Airlines review

My family and I purchased our Delta airline tickets online the night before our scheduled trip for an interview.  We arrived at the airport within the appropriate timeframe and checked in at the counter.  The agent was lacking professionalism and did not inform us of any rules that had changed at the airport.  The TSA informed us that Delta chose us to be checked thoroughly at the security check gate.  We had decided to carry on our bags due to the fact that I did not want to take the chance of losing my clothing for the interview.  I have two disabled family members with me and this process became very invasive.  My daughter actually was crying by now.  To make a long story short, by the time that we got to the gate, we had two minutes before take off.  I kept running and screaming for the agent at the gate to wait, but she did not even acknowledge me.  The agent even refused to wait for my disabled husband to arrive and demanded that he run (he has had a heart attack, 14 operations, and his foot partially amputated).  The crew on the plane was so nice to us and could not understand why this gate agent would not hold the plane for us.  They were not ready to take off and actually waited even longer for anyone else.  When trying to call customer service at Delta, the rep. argued with us and would not show us any empathy.  She could only say that buying tickets online the night before causes them to "red flag" us.