Eviction or No Eviction ?

Hello , Iam in the state of california and I have gained an eviction on my credit. My mother was the person who had initialized the lease agreement and I was living with her for about 1 year. I had left to live with my girlfriend / now wife prior (4months-6months prior to the eviction) The landlord claimed everyone in the house on the eviction and I was never served the paper work depicting any sort of eviction (inofrmation must have been held by mother). I tried talking to the law firm about the issue but they would not help me in fact they where rude and said that my mother had to pay to remove me is this legal?
Iam trying to purchase a home and this dilema is devastating. To complicate matters I have a letter of exclusion from the lawyer that my mother gave me. It exludes me from the eviction but I dont understand why he would not talk to me and why it is on my Credit.... Help!! someone!!