Disclosure - I work for a Mortgage Broker.
With all respect to the above posters, the service levels with First Active are absolutely atrocious.
I personally know of a major Mortgage Broker in Dublin associated with an estate agency that have their clients sign a waiver, absolving the broker for any difficulties due to delays because the client chooses to proceed with First Active.
Now in fairness, it doesn't sound like you have had the best service to date from your current broker, with regard to cover over the holiday period, but First Active are not helping the matter.
The broker should be able to provide evidence of when they submitted the pack to First Active, should you need to dig any deeper