[DSL M] Today, exactly mid-2yr-contract, I received an email saying "the requested changes were done to my contract"

This morning I received an email saying "the required changes were done to my contract". Except I have not requested any changes. I have noticed that there is a new item on the list: Unlimited surfing with maximum speed, that costs 15 eur per month and is added on top of my plan price (so 35,00 + 15,00 = 50,00).

Since I have never agreed to such a change, I wonder how they can do such a thing?

I did notice in the past 6-month period that there is a note on the "Mein o2" page saying the limit is going to be removed (limitation was basically: surf 2 months in a row unlimited. Then, if you also in the 3rd month go over 300 GB - until the end of that month the speed will drop to 2 mbit/s).

I also checked here in the Community and people have confirmed the limit was gone. Great, I thought.

Can anyone else confirm that they also received such a change to their plan?