Thanks aSwissInTheUS. No I am not the swiss company (I wish I could live in Switzerland), I put Zug in the location because I thought it was mandatory to put a location. No harm intended.
Thanks for the link!

EdwinNL, could you give me a link to the the debt enforcement and bankruptcy act.

Both: could you recommend a good swiss collection agency / specialized lawyer we could use to get the money paid? Or even better, a company which we could sell the debt to ?

Thanks