I'll pay Netstar when they pay me!

I sent a cancellation email in January. In February a payment was debited from my bank account. That should have been the end of it! I have now received invoices and statements every month since! For your airtime!?!?!?!?! This is a joke right? Please do show me the documentation where I approved being charged this? And now... I've been handed over to a debt collection agency! I will NOT pay for your airtime which was incurred only due to your pathetic level of service! I will also not be answering any of your phone calls any more! Will you pay for my time I have spent in answering calls, emailing again and again with proof of my email of cancellation, proof of payment in February, bank charges in pulling statements going back that far, and subsequent emails and calls? I will pay your invoices and statements when you pay me for these items required to try get rid of you!