Send SMS failed - message cost cause?

I have a Huawei P20 Lite and am at PremiumSim (o2).

Now to my problem:

If I want to reply to the Paypal short number in an SMS, the message came that this could cause costs (which it does not). In any case, I somehow clicked on No and now comes always "sending failed".

For normal numbers, SMS works fine…

I searched all settings in the phone and found nothing. I also set the "News" -App back to standard and also in the service world of the mobile operator, I find no such blocking.

I would have quasi due to attitude my card stuck in another phone and send the SMS.

It would be nice if you could help me.

You probably have a "third-party block", so you can't send SMS to special numbers or value-added numbers. You can cancel this lock on your homepage (my prizesim login) or via the hotline. A SymS to a special phone number (eg a five-digit) always costs extra and does not fall under the Flat.