Bankmed refuse to assist an old member, now I need to pay a late joiners fee because bankmed refuse to assist

I worked for ABSA until 2012. I have been asking Bankmed to supply me with a medical certificate to proof that I was on a medical aid. However they have changed service providers and cannot/ do not want to, assist me with this certificate. They have been sending me from pillar to post with no answer and no assistance. I have been retrenched and need to find a new medical aid. Bonitas is charging me a late joiners penalty fee because this info is not available. My new medical aid is charging me a late joiners fee because this info is not