Allianz Supplementary Health Insurance Covers Nothing!

We purchased supplementary health insurance, but it seems to cover nothing. What’s the point of having it then? Our entire family is covered under this policy. My father underwent an angiography, which turned out to be unnecessary, and nothing was found. No arteries were opened, and we still don't know why it was done. Despite filing a petition stating it had nothing to do with pre-existing conditions, our trusted policy covered none of it. I used to recommend this insurance to everyone around me, but it offers no benefits. Whether I pay upfront or in installments for each visit, it’s the same cost.