The burden of proof is on the other party (and their insurer) to provide sufficient evidence that it is "you" which was involved in an accident. That should include the basics such as where, when, what happened, their car etc.
You've then done the right thing by providing evidence you were no-where near, however, your insurer seems to be failing you by passing on the basic details of what has happened.
I would personally send them a very clear letter explaining that you were not there, you've forwarded proof, and you aren't going to entertain any further discussion on the subject until the details of the apparent claim someone is trying to make against your insurance are forwarded - which is definitely not an unreasonable request!
You've then done the right thing by providing evidence you were no-where near, however, your insurer seems to be failing you by passing on the basic details of what has happened.
I would personally send them a very clear letter explaining that you were not there, you've forwarded proof, and you aren't going to entertain any further discussion on the subject until the details of the apparent claim someone is trying to make against your insurance are forwarded - which is definitely not an unreasonable request!