Worst ISP and general service EVER

The absolute worst service from the worst ISP ever. I wish I could give it less that 1 star. How are these people even legally allowed to operate? No office. No landline. Useless website that links to a Whatsapp number with THE most unhelpful, unprofessional staff. My dad was unfortunate to have signed up with them and I have been struggling for 2 weeks to cancel and get my dad a new ISP who cannot proceed until this one is cancelled. They respond to Whatsapp messages but they moment I mention a cancellation, they ignore me flat. I was on hold on Whatsapp for 2 days before someone responded to me. I message at 7am, and get a reply at 11:30pm when I am asleep and then because I did not reply, they close the conversation. Can anybody please advise how to cancel this sorry excuse of a service? My dad has been without internet for 2 weeks now and unable to cancel. Somebody, anybody !!!