Customer service reps with difficult accents

I think I posted this question a few days ago but I don't see it here. Why not?

Some of the customer service reps have accents very difficult to understand.  What's the polite way to ask for somebody who speaks English more clearly?  All I can think of is to end the call and call back hoping for another rep who speaks English without such a heavy accent.  I know there are many varieties of English, but it's still difficult to understand many of the reps. thanks.