Need to reschedule KPN technician appointment, but wrong emailaddress in KPN account

Hello, my KPN account was set up using a wrong email address. I created a new account and filled in my profile with the right email address, and recently submitted a move of address without an issue. I was under the impression that this wouldnt be a problem. Few days ago, I received an SMS that a monteur would come by on the 5th between 10 - 12, but that is too early as no one will be in the address yet. It turns out I cannot change the appointment using my account with the correct email address. I received a letter that I could change my email from my profile but this is also not possible since I cannot login at all.

Can you please help?