Worst internet service provider

I have been with Supersonic for the past 3 weeks with the home LTE package. I have been experiencing speed issues at first and now for the past 5 days i am only connected without internet. I contact the technical department many times and they reset from their side. It then works for 15 minutes and goes back offline without internet. I require greater intervention by Supersonic, otherwise would like a cancellation without penalties as i am unable to receive the agreed service yet i already paid my subscription.