You can not simply „convert“ it. You should have reported your move in advance, Vodafone then checks if your contract is available at the new location, if not Vodafone terminates the contract without you having to do anything. You will have to sign a new DSL contract, which comes with a new 24 month minimum term (that is totally non-related to the cable contract, so you can do that right now). For support in English use WhatsApp, from the bit there you repeatedly request a „Kundenberater“, at some point you will get forwarded to a human.
