Sam's Club review: treatment of employees

I worked for Sam's Club for 5yrs. I was just terminated. I received my first write almost 2yrs ago when a fellow coworker and I had a disagreement and I raised my voice as I was walking away from her. Then in November I was told I was being written up for my attendance when I called out 2 days because my daughter had to have an emergency c-section. Then my grandfather passed away and I called out 2 days because we had to drive out of state. I was pulled into the office and told I had 7 unexcused since March and I was receiving my 3rd write up. I questioned my manager and said that meant termination she said no they had a new system. I went on through the holidays and new year busting my butt to prove I really loved my job and would do whatever they wanted, needless to say last week I had a member call upset that glasses he ordered were still not in and he had been waiting for 2wks and we told him 7 to 10 days. I checked into it and apologized because his frame was on back order he started to raise his voice saying he didnt want.my excuses he wanted his glasses, I explained again his frame was on back order and do to the holidays a lot of our orders were delayed again he was stating he didn't want to hear my excuses so I apologized to him saying I would have the lab send me his lenses and get his frame from another store and would have my manager call him he again yelled at me and said he didn't want my excuses so I told him sir I will have my manager call you in the morning thank you goodbye. I immediately printed off all this gentleman's info to contact my manager and explain the situation. In the meantime he called back and spoke to a store manager telling her I was rude and hung up on him. Previously when we had patients that acted like this that made the situation uncomfortable and we in anyway threatened and the member was not going to calm down to speak to us in a normal tone we could remove ourselves from the situation as long as we made our manager aware of the situation, which I did. On Friday of this week I was taken into the office and told I was terminated for being rude to a member