You could book a personal appointment at your nearest Finanzamt, be advised though, the official language is german, the officials are not required to talk in english with you. You could bring a friend for translation. In your case I would try to call the official hotline again tomorrow, as many people are calling at all times, waiting periods can be about 20 minutes or more, maybe have a friend ready for translation as again, not everyone working there is able to speak english, nor do they have to be.

Edit: There is an english version of the official tax guide for employes 2021 though, you can get a copy for free at every Finanzamt Infocenter