Spam hits my Skype-connection

Not sure what is happening today, but suddenly I get swamped by spam messages over Skype. On the screenshot you see one of a few dozen that came in today.
Skype was being used now and then for spam, but today it went all out of hand. All the messages seem to come from two or three Chinese sellers of Skype applications and it is really a nuisance.
I'm on Skype in the 'invisible' mode, so I can actually sometimes get some work done and that stops actually legitime services like the RSS-provider Anothr.com, who does not seem to work when you are 'invisible'. But spam does get through, for sure.

Update: That was quick. This evening I switched on Skype and it offered a new service: it allows me to receive only chat from people on my contact list. Have started that of course right away.