Tier 1 PSW visa issue

Tier 1 PSW visa issue

I am currently in Tier 1 PSW Visa which is due to expire on April 2012. I am working as a full time employee in a private company which contracts us to another firm. My salary is £23,000 per annum. I will be completing 6 months in the company in March. My only option to continue is to switch to Tier 2 Work Permit Visa. My concern is, Is there a possibility for me to extend my visa even if my employer is not in the list of sponsors, but I meet every other criteria. Since I am switching from PSW, Is it enough if my employer gives a letter stating that I worked with them for 6 months, my salary details etc. or Is it compulsory that my employer should be in list of sponsors for me to get Tier 2.

Kindly help me as I am not clear with the wordings in UKBA website. It says ' You can be assigned a certificate of sponsorship if switching from PSW'

Thanks in advance.

Tier 1 PSW visa issue

Tx 4 the reply. So it means there should be a certificate of sponsor from the employer compulsorily even if I am switching from PSW. Just a letter won't be enough.. No other options left for me.. But to leave this job.. Tx anyways...