There are no limits. If you are going to run bandwidth hogging peers/clients/servers then do it after midnight and before 4pm. Do it before and you risk action being taken against you. This sounds like at least a warning and possibly a large bill/fine.
I just called Cablecom to ask about the monthly bandwidth limit. First they told me that it was 20 mbit (which is my speed) than they explained actually there is no limit. So I asked, I wanted to download some movies, he said, oh there is no problem, you can download as much as you want. 20 mbit is guaranteed for all month long.
Also before coming to Switzerland I used to be a UPC (Chello) customer (UPC = Chello). At that time (about 1 1/2 years ago) their fair use policy was 300 GB - according to what I'm hearing since then, they are not even enforcing that anymore (in other European countries)
Bottom line: IF there would be a fair use limit, it would be at leat 300gb/month, but quite possibly there is none anymore
Now I wish only, they'd take over the pricing from elsewhere: 60dl/gb ul for 25 CHF, 120dl/10gb ul for 30 CHF ... but I'm not holding my breath for this to happen