Is client Letter mandatory for H1B filing?

Hi,

I am applying H1B this year through a known consulting compay in US( small company with good H1B success rates).

The company suddenly says that they are unable to get the client letter.

Is client letter required for filing H1B?

Any suggesstions/alternatives for me as I desparately want to file visa this year.

Thanks in Advance:)

Client letter not required while filing, but it might be asked during approval as RFE, or may be during stamping

there are many chances of asking