Call centre taking hours (might not even be an exaggeration) to answer calls

I have been on hold with the call centre for 35 minutes already (and still counting) to simply change the contact information on our account to that of our new tenants. It has already been more than half-an-hour on the phone and I have not even had the privilege of speaking to an operator so I can't even ask if there is an alternative way to simply change the contact details. I also sent an e-mail asking if there was no way to do this via e-mail, because no one has this ridiculous amount of time available in the day to just be on hold, but have not received a response yet. This is unacceptable and hopefully your response in an emergency situation is exponentially quicker.