Contact o2 customer service.

the phone line is busy all the time

Then you'll have to wait in the telephone queue. 

@raketa Did you use the number for the English speaking hotline? ->   089666630081

Hello, yes, exactly the same number, and I waited half an hour for an answer, and there's nothing.

@raketa Did you use a German SIM card or foreign SIM card (number) for calling the hotline?

German SIM card

@raketa but you still get the greeting in English when you call?

Yes, in English, and then to continue the conversation in English I have to press 1 (and after that I wait a long time without an answer).

@raketa Try the WhatsApp chat. If you have luck you get an english typing operator.

https://www.o2online.de/kontakt/whatsapp-chat/

Hello @raketa,

have you managed to get through to our support meanwhile? If not, please let us know and we will order the router for you as well. Please let us know which one you have chosen as well in this case.

Best regards

Giulia

Hello! Yes, I think I ordered the router, thanks (if it’s possible could you check it please)

Hello @raketa,

our logistics department have received your request and will send the router as soon as possible.

Best regards

Giulia

Hello! That’s good! Could you please tell me status of delivery because I have contract from today and don’t have router and connection to the internet 

Hello @raketa,

you should have received the shipment information by email meanwhile. The router will probably be delivered today.

Please let us know if you have any further questions.

Best regards

Giulia