Outgoing sms formatting broken - no outreach possible

I connected the sms-provider "Seven.io" (former Sms77.
The reachout from clients account works basically but it looks like in following Screenshot from my phone.
- Instead of an Paragraph the system writes "nn"
- Instead of a line break system writes "n"
- Instead of "ä/ö/ü" system writes Hieroglyphics

How it looks (even the link is not clickable):

How it should look:

You find it in this campaign:
https://reputation.reputio.de/campaigns/0aeb0cac-1633-4bdc-ae4e-4ddf2f3c0255/edit