Airtel — postpaid bill payment issue

After surrendering my hotspot sim, i have no way to pay the bill but to visit their office. Upon visit three different times, their system was not working so could not pay the bill. Then started receiving calls from their collection team and they were talking like they were talking to a thief who has run away with their money. I still have 5 family postpaid connections, this is of no relevance to them. When i visited the tired time to hsr layout sector 2 airtel center, the person their was very rude and upon asking if there is any other way of payment he was very rude in saying that you have used the service so you have to come and pay whenever their system is working. People have their work and other engagements and visiting airtel center for paying airtel one bill manytimes is not the highest priority. They should have online mode of payment. I have not delayed any payments during the usage as i had facility to pay online, but once the sim is surrendered there is no way to pay online and when i visited their center they could not accept payment as their system was not working. They are not bothered about customers pain and they treat customers like they have given them something from their pocket.

Request this issue to be addressed and payment cheque collection to be arranged at my doorstep.