Premium penalities for late joiners

My parents, both pensioners, dad 80 mom 75 are on Bonitas Boncap option. This option is terrible and doesn't pay for treatments required. So I asked to upgrade the plan to the BonSave option after talking with my dad and making sure he could afford the plan change. Now they are adding a late joiner penalty of R2490 additional to the premium. Now this plan is unaffordable. My father has been a member of a medical aid since 1971 when he was employed with Iscor group. This medical aid no longer exists so we can't obtain a medical aid certificate. As per medical aid rules is you can't provide this prior to 1 April 2001 they will add late joiner penalty fees. 1971 was the stone age of technology. How are they supposed to get it if the medical aid closed down? 0.75% is now multip**** with the actual policy premium. I got proof of all his medical aids as far as 2008 but prior to this he was with Ferromed and then Kopano health who declared bankruptcy so how do we get the proof. It's ridiculous how medical aids rips off pensioners