Struggling to secure job

Hoping for some advice here.
I am experienced in my field, CV impressive enough that agencies are keen to contact me, but after an initial enthusiastic phone call, most drop off the radar.

I've managed to go to 3 interviews, so some agencies do follow through.

My question is what could I be doing wrong when I deal with them? Not grovelling enough, not speaking clearly, asking for too much money?

It's none of these btw but I am a foreigner so speak with an accent. I have a British passport.