Paytm Mobile Solutions — I didn't use single rupees from paytm postpaid yet they ask me to pay bill

Hii...my name is hardev...my complaint is against Paytm postpaid...i activated paytmpostpaid and use it...but then i pay my bill of 368 rupees...After that i didnt use single rupees of paytm postpaid and suddenly one day i recieved call from them and they said u jsed 300 ruppees and now you have to pay ...after that they including penalty charges for every month and now i have go pay 710rs ..

I have Proof that i never used single rs after my first bill payment...proof in picture
They call again and again ... Please help