Hi Sevket, welcome to the Community and great that you are going to Switzerland! It's good that you are well prepared for your trip and possible costs and I completely understand that you want clarity about this. I'm happy to give you that. With your old Tele2 subscription, Switzerland falls under the Zone EU bundle. I read that my colleague previously indicated something different, but this is not correct. I'm guessing she was confused with new Odido subscriptions. Switzerland is not included in the bundle.
The following applies to you: calling and texting are excluded from your bundle. Receiving calls and text messages is free. With your data bundle you can use 20GB in Switzerland. As soon as you arrive there you will also receive all the information in a welcome SMS. In Switzerland you will soon be able to connect to the Salt , Sunrise and Swisscom networks .
Is it so completely clear? If you have any questions, please feel free to ask. I am here for you!