Well, if you order cheap, you get cheap.
The app seems completely technically outdated, not native iOS.
Submitting receipts: no photo upload, not even according to user feedback here. Only standard English answer but no feature.
Entering the billing data is extremely annoying because there is a lot of information. With a modern app using image recognition, it could be read out and pre-filled (treatment date, etc.).
Weak, Barmenia can do better.