Airtel — starting the data pack plan by deducting from main balance

Website:

www.airtel.in

I wanted to start a data pack which is given as best offer for you by airtel by deducting the required pack amount from my main balance.in the airtel app i am having an option to pay the charge through main balance however when i tried to proceed further by select in that option i am getting an error message as recharge un successful due to technical error please try again. When i repeated the same procedure again it gave me the same error several times.
After getting this error number of times i decided to get help from so called airtel customer care but instead of helping me in recharge the customer support directly denied that this option is not available you have to visit a retail shop and pay the money and start the service. I tried to convince him that i do have an option of recharging from main balance in airtel app but he refused and asked me to drop a mail by taking the screen shot.
I am using airtel from last 10 years but this kind of support is not what we expect. We have our money in main balance we want to use it else where but the company is not allowing me to do that. Even i asked the support person if i will be able to send the money from account balance to airtel wallet he said no you cannot. I think if a person does a recharge of certain amount then he should forget about it and assume that the money is gone now and these corporate vultures will won't let you get back your money.
Please take some necessary actions on this. Uploading the required screen shots for supporting my claim.