Hi I'm an RGN and am experiencing this too!
I joined 4 agencies,and have had to have 4 CRB's done,I have applied to the Hospital bank, and had a CRB done.
Apparently:
You have to have a CRB with the Employers name on it.
In my case,there was one "going through" at the same time as another one was started!
It takes roughly 6 weeks,but you can check the status by making a note of the reference number when they send it to you to fill in,and go on the website,and type it in.
The other bit of bad news is they are Annual requirements!!!
So every year you have to fork out for it.
In certain cases the Employers will pay for each one,or the Agency,but usually not unless its NHS.One of the Agencies I am with allow you to accrue points for each hour you work,and you can use them to "pay" for a CRB,or uniform or Study days.
Oh yeah,one last thing is the mandatory Study days such as Moving and Handling,you sometimes have to pay for them as well,and they need renewing Annually too!
Great eh? Hope the info helps though.