Want to work on L1B visa in spite of H1B approved petition

[jghere4you]

I am working with company A on L1B visa (Visa already expired but I94 is valid until 2015 and company's blanket I797 petition valid indefinitely) 
Company B filed for my H1B (with COS) visa which got approved on Sep 04, 2013. Now, I want to continue with company A on L1B visa. 
Note: I cannot go out of Country as my L1B visa is expired. 

I have already asked company B to withdraw my approved H1b application as I cannot join them due to some personal reasons and have kept a record of that email - haven't heard back from them yet. 

Is that sufficient for me to keep working on L1B visa with company A i.e. without any acknowledgement or confirmation of withdrawal from company B or USCIS? 

Thanks in advance! 

[jairichi]

I am working with company A on L1B visa (Visa already expired but I94 is valid until 2015 and company's blanket I797 petition valid indefinitely) 

Company B filed for my H1B (with COS) visa which got approved on Sep 04, 2013. Now, I want to continue with company A on L1B visa. 

Note: I cannot go out of Country as my L1B visa is expired. 

I have already asked company B to withdraw my approved H1b application as I cannot join them due to some personal reasons and have kept a record of that email - haven't heard back from them yet. 

Is that sufficient for me to keep working on L1B visa with company A i.e. without any acknowledgement or confirmation of withdrawal from company B or USCIS? 

Thanks in advance! 

If your COS is approved from L1B to H1B and you want to work on L1B then you need to exit and enter US just before your H1B start date. Alternatively, I heard that CBP offices do issue I94 if you want to extend your current status on L1B. Wait for other members opinion