CA: Notice or not?

[WLVBRIT]

CALIFORNIA. I have a Letter of Employment which states "You will provide Company, and Company will provide you, written notice, at least 90 days prior to the termination of your employment.. other than for cause".
6 weeks ago I was given an unsigned letter terminating my employment (job elimination - not 'for cause') and offering continuation for 90 days of salary and only _health_ benefits. Despite negotiations the Company won't see the difference.
The intent was that termination (and thus termination of ALL benefits) would be 90 days after the notice, including 401k, stock purchase, vacation accrual etc.
The Company required me to return all my documents, computer, cellphone, keys etc and leave immediately - effectively "locking me out". I emailed the President asking him to confirm that I was not to perform any further duties or enter the building, but there was no reply.
They did NOT pay me on that day but have paid me on the regular cycle since. I have NOT received any accrued vacation payout. To my mind they have made many mistakes - what Codes can I cite to get their attention?
Is an _unsigned_ letter (and brief conversation) valid notice in CA?

 

[robampcar]

salary,salary exexpt,hourly.either way california employers cam eliminate position or cut staff at will.by paying you "severance pay" they can fill your old position before 30 days..has your old position been filled? if it has ask your question again...but again 3 monthes pay,cool thats better than edd.