Cleaning cookies doesn't work, this happens on several different devices (home and work computer, phone and tablet).
I can log into my vodafone account normally, but not ziggo (this is where I get the error -1)
If I hit back on my browser, and click on the menu, it shows as being logged in.
Here, if I click my ziggo, I get the same error, if I click my profile, it says oops, you tried to login to my ziggo with a my vodafone account.
But if I try to create an account, it doesn't work (email already in use), or if I try to merge it doesn't work as well as I said already.