Delta Airlines Delta's Horrible Customer Service - Changed Flight Time - Failed to Notify - Refused Seats to us Nationwide

Here is an excellent example of POOR CUSTOMER SERVICE that we experienced on a recent Delta flight:

We purchased airline tickets in April with a departure time of approximately 1240pm from LAX to ATL. After we arrived in the airport (months after purchasing them) we were told our flight had changed from 1240pm to 11am. The woman at the desk, Annette, confirmed that Delta had NOT informed us (even though they had months to do so) that the flight had changed in anyway even though they did have our contact information. I asked for a supervisor and Sergio R came to the desk. He stated that there were no seats on the next flight in order to at least try and make our connection. When I asked him to confirm he said "I'm not going to lie. We do have first class seats available, but I'm not giving those to you". Now, I don't care what seats I get... if Delta screwed up and didn't notify me of the times changing I want a seat that I paid for at the time I paid for. Nothing more... nothing less. Sergio R eventually found seats and told us to proceed to the gate and he would call up there to confirm them. When we got to the gate, I told him that Sergio got us on the flight and the woman laughed at us and said "oh no, you're on standby. There are a number of people ahead of you on this flight". So basically Sergio flat out lied to us to get us on our way and no longer his problem. I don't understand how customer service can perform in this manner and not expect repercussions. Not only this, but when we did eventually get on a flight, our seats were already assigned to someone else and they had to sort it out on the fly. Not to mention a "mix up" with the catering truck and having food being severely limited on this flight. When trying to contact Delta about this after the flight, I continuously get sent to a different phone number and eventually got their "Corporate Customer Care" department which basically tells me to go to a website. When I do get a live person after using automated options OTHER than they suggest, I am told they will get a supervisor. However they forward me to the same "go F yourself" recording that eventually hangs up on you. I have not seen this level of unprofessional behavior from a business in a long time... in fact I'm not sure I have EVER seen it to this degree.