I am so disappointed...

I am so disappointed to NestarGo because I struggle to cancel with them ..I have waited 30 days cancellation period but they have failed to follow up to cancel with them,still after cancellation they still debited my money now they have send me to credit solutions for canceling with them so I tried so many times with emails and calls to cancel this thing of them but still nothing they promised to call me but nothing i am so disappointed my question is how to cancel ?