Ok, in your second last to post you said that you don't have cable. Now you say you do - but you blocked it. Which one is it?

How does blocking the cable access stop you from getting the TV signals that are broadcast over the air? You are still liable for TV tax whether you block your cable access or not, despite what the cablecom guy might say. If you really want to confirm the law then talk to Billag, not cablecom. In addition, you are already paying about 20 francs per month in your Nebenkosten (additional costs as part of your rent) for the TV part of your cable access. The fact that you blocked the port will make no difference.

So I think we've established that you do have cable, and unless you rip out the tuner from your TV and get rid of your radios you'll be paying TV tax. So the only thing you have to decide is whether you want internet or not - a difference of 30 francs per month (minimum). You may be spending more than this on dialup access already, especially if you count the cost of your phone rental.