(Help) Orange won't let me cancel their services.

Hey, sorry for using English!

So my issue is that I switched over to another Internet provider and Orange is still sending me the internet bill. Now so far this is my mistake since I thought it would cancel automatically.

So I went to an Orange Shop near me to cancel my subscription. The guy in the Shop sent a request to Orange to cancel my subscription and said they will contact me via email or call me.

A couple of days passed and they sent me an SMS saying they couldn't reach me (not true, I checked all my emails and missed calls 10 times) and that I have to call them at number 5000.

So I tried to call them at 5000 and they immediately hang up. Then I went to their website and found another number (+32 2 745 95 00). I called them at this number and again they didn't pick up.

So I waited 1-2 days and tried calling them again on both numbers and as you guessed it, nobody picks up.

Can anybody help me out with this? How can I finally cancel these guys and why do they make it so hard...

Thanks in advance.