Airtel — harassing by calling on unnecessary issue

Hi, I have hotspot with airtel sim, number: [protected]. this number linked with my alternate number: [protected]. In april-May, i got a bill of Rs.5663.76. I called them up for asking why is that so.? There customer care executive said that i have changed my plan (which I didn't requested nor I was not informed about it ) and for that plan, bill is the annual one. So i told him, nobody called me regarding this nor i received any sms or mails. How can anybody activate this plan without my concession. I told them to block my number ([protected]) as I will not use it. I dont like this service. Please keep in mind I was still getting IVR call and normal calls to pay the bill, even though I blocked my number and I had complaint it. I did follow up on this complaint and request to block my number after 3 days and the confirmed that. BUT I AM STILL GETTING IVRS AND SMS AND CALLS TO PAY THE BILL. Yesterday I was fed up, I again called the airtel executive (NAME: AMBIKA) that I already have blocked that number, and I have destroyed the sim, why I am still getting the calls from u guys? SHE ASSURED ME THAT IT WONT HAPPEN, but its not the case. I am still getting call, and now if I block it, they are calling every hour. THEY ARE HARASSING ME. There SERVICE IS JUST PATHETIC.