zaq Welcome to the community!
We will be happy to answer your questions as follows:
From the subscription upgrade page at MyUPC I can see the price to be 59 CHF per month (without UPC TV). Is this the total price I’m going to pay monthly or is it on top of the Basic Internet, which is 39.90 CHF per month? I.e., after the upgrade, would I pay 59 CHF or rather 108.90 CHF per month?
The price you see in the shopping cart after submitting the order is the total price including the cable connection fees, which you have paid separately until now.
I think for new customers UPC offers 100 days cancellation option. Does that apply also when someone upgrades their subscription?
No, the 100 days right of withdrawal is only for a new registration.
Currently the coaxial cable with TV signal is connected directly to my TV. If I upgrade my subscription to Internet 100 but don’t add UPC TV, would TV stop working?
No, the basic cable connection remains as you know it today. But if you want to receive more channels, you need a UPC TV Box.
Greetings
Daniele