Hacked Proximus account ?

Hello, i moved to a new address. It took proximus 2 months to install the internet connection on my new addresse. This wednesday the technician finally placed a new the router connection.
Still, since wednesday, I have been contacted by proximus 3 times to make an appointment for installing my new internet again .... There is a big mess, apparently several parallel orders and no one is able to sort it out.
I also use proximus account for my email. I have two different proximus.be email addresses, one main and one secondary.
Today I have received a strange mail on my mobile phone. It was a regular request to make a new appointment with proximus technicien. It was sent from info.order@proximus.be and from my secondary proximus email address. Is it possible to send one email from 2 different email adresses at the same time?
This mail was delivered to my main proximus address and another friend of mine who is not related at all with my proximus account.
Is this possible? Please see the uploaded screenshots.
I contacted the proximus service 6000 to announce this inconvenience. It took a while till they understood that I dont feel safe using my proximus account and internet.
They gave me another number to call 0800 22 301 to ask to reset all my passwords.
This number doesnt work, my calls are immediately interrupted.