Chilli.....
If you're inadvertantly inside CAS then, rest assured, the controller is already ontop of you and, where necessary vectoring away his IFR traffic to maintain the separation it should be affored. You don't need 7700 for this.....
If you suspect you're inside CAS then your call should be to that unit first - if they can't help you (you're probably not inside their space) and will recommend a call to D&D.
If you don't have the nouse to be able to talk to someone on the radio - you shouldn't be up there in the first place - and certainly nowhere near CAS!
DD