Having had a good experience with O2 in the UK, when I moved over to Germany I ordered a SIM-only contract for my unlocked iPhone. The SIM card arrived, and I followed the instructions to active the SIM.

Unfortunately, although it can call and use LTE, it cannot receive SMS messages. This means I cannot register for a Mobilfunk-Kunde account, as I cannot receive the confirmation SMS. I also cannot receive SMS messages from Apple, PayPal or other German mobiles. 

I have checked that the settings shown in https://hilfe.o2online.de/english-o2-community-43/mobile-settings-457904 are correct, removed iMessage/FaceTime, reset my network settings and even tried the SIM card in other iPhones. Nothing has resolved the issue. 

Please could you suggest what I should do next?