The EHIC entitles you to healthcare in the EU. No credit card required. No idea why you decided to pay.When ever I have been in Europe if either my wife or myself had the need for a hospital we automatically paid by credit card. Even though we showed them the E11 card or whatever it’s called these days. Although in fairness I was able to claim most back from my insurers. (After the standard charges were taken out)
Another triumph for Brexit that we won’t have that benefit any more.