C-permit

When getting back from Barcelona I had a large stack of envelopes waiting for me. Mostly bills, but also my C-permit. Finally! Only I don't get what the difference is from the B-permit I had which was valid for 5 years. I thought a C-permit was permanent, and that I wouldn't have to renew it. Wrong. Says on the new permit that "kontrollfrist" is in 5 years. Means I will have to go through that painful exercise with getting all the documents from the police, the "kreisburo" and whatsit. Ah well, 5 years is a long time... PS. Ze Swiss are not a trusting bunch. Especially towards us foreigners. It just doesn't matter how good and trustworthy you are, they don't believe you. And I doubt they ever will...