A change from a 24 month contract to a Flex contract is not possible. 

Please read this:

https://hilfe.o2online.de/english-o2-community-43/how-to-do-a-cancellation-of-my-dsl-contract-due-to-moving-abroad-508314

Hi @bua123,

thanks for your message.

Was the message you got from @blablup already helpful for you?

Even though you cannot change to a Flex-tariff, you can cancel your contract to the exact date when you will leave Germany. So, please do not send us a cancellation to the 25th April 2020, but to a later date.

We need to receive the cancellation until 25th January 2020.

I hope that this solution is helpful for you.

Loving greetings,

Tobias

Thank you for your answer @blablup & @o2_Tobias 

By the way, if I cancel the contract, I have to return router with the cancellation letter before  25th January 2020, right?

Many thanks!

Bua

Hi @bua123,

first of all, we only need your cancellation letter.

Before you leave Germany, please return the router by using this link: Return of router

I hope I could help you with this information.

Loving greetings,

Tobias

Hi @bua123,

as I can see, you already sent us a cancellation letter. Therefore, your contract will end on 25th April 2020.

If you have any further questions, do not hesitate to contact our English community.

Loving greetings,

Tobias