My MacBook Air runs out of battery all the time

My husband bought me a brand new MacBook Air. The battery will be completely charged. I use it for 30mins, come back a couple days later and its dead. This happens CONSTANTLY!!!! Due to the fact I was unaware that my computer was dead AGAIN when the automatic software update was scheduled. I had a couple reminders to install surf rf but i was very busy didnt do it. Plus its supposed to happen AUTOMATICALLY. I set it up to do so. Now I go to log on and its so dam slow that my computer times out or it will spin indicating its loading then several minutes later the screen will automatically close out and the window to the dictionary will open. I contacted Apple in regards to it and they told me that I have to download big surf smoothie Maxwell. OK so I paid over $2000 for a brand new computer. If i want to have access to its content I must do as apple says and download the software update they want me to have. Essentially I’m in “time out” due to my insubordination. So now I must take time out of my busy schedule to drive to Apple do troubleshooting to get my computer working. For what I’ll because I didn’t want to download half where they told me I should not slow down my system as much. I have almost every Apple product that you could have iPhone Apple Watch iPad iMac air Mac Pro & i just feel this is a load of crap that my access is non existent. Fine for it to lag a bit but to not let me even open an internet browser or my email at all dictatorship mentality. Luckily i dont have any important deadlines for work. You pay the big bucks, you expect quality. This is acceptable!!!! Does anyone have any suggestions? “Tech Support” instructed me to shut it down & restart. Now it wont come on at all urge!!!!!!!!!!!!

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