Airtel is harrasing me with unlimited calls.

I disconnected the airtel wifi in December after obviously tons of problems. And the thing that went wrong is, the airtel engineer who took the wifi router and cable did not update that to the company and the company thinks that i still have it with me. Evenafterw multiple complains they won't stop calling me or arranging delivery pickups. I have to ask every driver to not come to my address. This is unbearable now what can i do. Please help.