Airtel — conversion of postpaid no. to prepaid

I called up Airtel customer care at 121, an executive guided me the process of conversion from postpaid to prepaid.
Then I went to an Airtel Store for the same.

The store people told me that they don't have the application form for getting my no. conerted to prepaid in Jharkhand as my postpaid no. is of Andhra Pradesh. And to my surprise, they even told me if I want to keep using this no. I should take the cheapest plan and keep paying my bills.

I called up customer care no. who told me the same process of conversion to prepaid again as told earlier by them.

Next day, I get a call from customer care telling me a different process for conversion. They gave a call back only because I gave them a poor rating.

Moreover, they expect me to pick up their call as many a times as they call me up during the day.

They have wasted a lot of my time and energy on this simple task.

I asked them to provide a solution in email.

I got an email which says to send an sms to 1900 with PORT (Mobile No.)

I followed this step too. Now the company needs to give me UPC according to the mail so that I can go ahead with the process of conversion from postpaid to prepaid.
I have not received UPC yet.

Please provide solution asap as I don't want to pay my postpaid bills without any reason and convert to prepaid as soon as possible.

Please provide a solution to my problem.
The company is using the policy of ' Let the buyer be aware' which is quite shameful and a big spot on such a big company.

Thanks to Jio fir providing great services at such a good and economical price.