Change from Tele2 to T-Mobile thuis subscription

I got an letter from tele2 that I have to switch my internet+tv+bellen using KPN-cable to T-mbile thuis. I  have internet from T-mbile now. It works well.

Do I need to do something about my tele2 contract for the internet+tv+bellen? I want to be sure that I do not pay double cost, both tele2 and T-mbile.