End client letter is not available.

I have got RFE for H1B.They required the end client letter,but my client will not provide such letter.I have submitted BRM letter.Will it suffice the purpose?I have responded the RFE on 1st August,2013.Till now have not got any update.I also don’t have the petition number with me,my employer has not shared it with me.

I have seen few cases where BRM’s vouching for client letter has worked. But I think that’s case by case basis.