Cancel internet but charge bill

I changed to T-mobile Home from 30-04-2020 (official date). As T mobile and Tele2 are same company, T mobile canceled the old subscription. I have a written email from T mobile. I also have the cancellation confirmation from tele 2 by email.

However, tele 2 sent email on 12 May with “ Today you are disabled services) ”, saying “ Because you pay a month subscription fee in advance, it may be that on the bill this month cost of a time when you no customers anymore. If this applies to you is the case, you will receive next month a bill that we settle this. And charge the bill for May.

T-mobile also charged the bill for May. I pay 110 euros in total for only home internet, which is rediculous. 

Logically, tele 2 subsciption had canceled on April 30, and started T-mobile, so I should not pay to tele 2 anymore.

Tele 2 doesn't answer by phone today, could you please solve this problem?

Thank you.