pre-paid to post-paid conversion

Hi, recently I have asked Airtel services to convert my prepaid to postpaid and told me that I can use my existing SIM card after conversion. On one fine saturday day got couple of calls saying the conversion would start now and the SIM services will not be possible for 30 mins. But my SIM is still not activated. It’s more than 24 hours now. Initially every told that conversion would take only an hour or so. After 24 hours when I called the people they don’t give proper response. Agent says I have to wait tomorrow to get the new SIM and activate the same. This could have been informed during the process when the conversion starts. Now I lost my contact. And would suffer with this. Please consider this as my complaint and do the needful.