[Resolved]  Idea Cellular — without any information barred my connection

Address:

Valsad, Gujarat, 396171

I was using idea postpaid connection ([protected]) from last 6-7 years. After using many years i convert it to prepaid (June 2017) with full & final payment of rs. 550. It is active with prepaid same no.
My mobile permanently barred without any information. When i call customer care that the system showing my postpaid bill is due. I told him that is that possible, without full & final payment idea porting my no. From postpaid to prepaid? Than they asking me to submit receipt in nearest idea office. Today when i go to nearest idea office, they asking me to rs. 980/- is due against my postpaid connection. How it is possible?