Trying to obtain 2016 and 2017 tax certificates for my husband who was paying the premiums for the last 12 years

I feel like hitting my head against a brick wall. My husband (according to the divorce agreement) had to pay for his ex-wife's medical aid. It was then with Liberty and was advised that I must now contact Bonitas. She has changed her contact details and he even went to her house but she has moved. He needs, as you are aware, the tax certificates for SARS. All I get told is that he must get a letter from the principal member giving permission for Bonitas to give them to him. I keep on saying that he cannot as he has has no contact details. This is really ridiculous as he is the one that has been paying the premiums every month