Penalised: overseas health insurers don't count

Have finally joined discovery- solely for vitality card and the virgin gym benefits. Despite having had health insurance in countries such as united kingdom, united states and australia- discovery views these as substandard it seems and, despite being an expat so global policies are obviously what i have had, penalise me not only with a late joiner fee (money for jam that one! what a rort. 20 years of overseas medical insurance not good enough for them!) but also with a three months exclusion. Incredibly....this includes any unforeseen medical emergencies. Amazing- i unfortunately end up in a car accident and not a cent is covered. I offered in fact to give them three months upfront immediately...financially after all its the same for them and I'm happy to pay them off- and was told i couldn't do that. What is worse- you have to sign on the acceptance form that you will immediately stop an existing policy when you sign up to Discovery. Im struggling to understand an insurer that is forcing you to be un-insured. I was told it was at their underwriters discretion- i asked for them to be contacted and the matter rediscussed- and was told that that would never happen. not impressed.