Proof of premium request.

I am beginning to regret joining Flexicare. My first premium just went off Flexi care and all I am requesting is proof of premium and the rude response I received was 'we don't do that". The medical certificate or the welcome letter do not show or state the premium. All I am asking for is a statement proving how much my premium is I cannot go by voice only. I need to claim from work and obviously they need some tangible evidence that I am paying that amount but how can I prove that with a voice. Everywhere you subscribe to you are given some kind of document proving how much your premium is why is it different with Flexicare? even Auto and General gives you a policy document stating the premium. I am considering returning to Momentum to think I joined flexicare because I am big discovery fan clearly loyalty is not going to serve me well.