Airtel — Converted prepaid to postpaid

Address:

197-a/7752, kannamwar no 2, Vikhroli east, Mumbai 83

REMINDER 2

I am using morethan 8 years Airtel prepaid no [protected], last 2 days before I recharged Rs. 399 for 54 days, and it's not working then I called customer care they says your no is converted prepaid to postpaid. Surprise when customer care says that you by doing must be selected Post paid plan. I need my no to convert on my previous same prepaid plan or else I will have to complain consumer forum.