Certificate of application validity

Hi,

My wife a non-eu has been issued with her permenant residence card however her employer are now requesting right to work proof between a date between the date of the COA and the date on the perm residence card (specifically 07/03/18 and 16/05/18).

This is strange. They seem to think the COA is only valid for 28 days but a ECS check is valid for 6 months. So they're asking for the ECS check for the above period. I don't know if they actually did this.

I thought the COA was valid for 6 months, not 28 days. Does anyone know of an official home office link which confirms how long a COA is valid for?

The employer has received copies of the COA and the issues residence card with confirmation of permenant right to work. I'm a bit lost as to how we could provide proof of right to work during the period they want.

Any ideas?

They just need someone who read English to realize that a Long COA is valid for 6 Months