EEA4 and new job offer, advide needed.

Hi

I sent my EEA4 application off 3 weeks ago and subsequently Ive been made a job offer, the problem is the employer is really pushing for some form of residence confirmation even though Ive explained that as a EEA family member I have the right to work (Ive provided evidence to back this up, passports, NI, birth certificates etc). Im supposed to start working for them in a weeks time, my concern is if the COA has not arrived in time I may lose the offer. The HO has been relatively unhelpful with the situation and what Im wondering is if anyone has any advice on what I could tell or show the employer if waiting for the COA becomes a problem; or is my best bet to just keep contacting HO.

(A bit of background information in case it may help, I arrived in the UK in 2001 with EEA parent on a family permit, had a 5 year residence stamp, I should have acquired PR on or after 30 april 2006, I have been studying from 2007 till this year.)

Thanks and I appreciate any thoughts anyone has on the situation.