last warning to be fired

[R9505]

i live in california, and i work on a ampm store and my manager told me that supposely 3 persons said that i don't want to work as a team but now i figured out that she lie to me and only the same girl that is always talking about me said that i told a bad word to a girl that works there that is true but my manger almost kick me out for that i didin't wanted to admit it but she was going to fire me she told me that is my last warning and i don't know if the same girl told that manager that i talked also about her cuz the next day she yielded at me and for the first time on a year she told me a bad word i do my job and 2 months ago my manger told me that maybe i was going to receive an increase on my paycheck but she didin't give it to me. i don't think that is fair to kick me out for that cuz 2 girls have done worst things like one was always grabbing sodas,everything from the freezer without paying and food and she was always sitting a chair on the register and the other was always taking 1 hour of break and she had to take only 30min i told my manager that but she didin't kick them out. but i think that the owner of the store doesn't know that. what should i do i plan to get some evidence like videotapying