I contacted Nokia Care and they told me that the update for Switzerland has already been activated, so they told me to completely reset my phone and to try updating again.

After the reset, there were still no updates, so I now updated using NSU.

Nokia Care also said it could be a problem with my carrier. However, I bought the phone myself just like my brother who has got the same carrier. The only difference is that his phone is from Austria and all the updates were found by his phone automatically.