Airtel — information mismatch between customer care system and *121*51#

On 26th feb got a message stating my balance was deducted. When i checked *121*51# 57.83 rs balance was deducted on 26th feb at 12:06 am. But i was sure i had not used the data at that time hence i called customer care. They told me 57.83 rs was deducted on 25th feb at 10.15 pm.
Need to understand why there is a information discrepency between the two sources?
I am sure i had not crossed my 1 gb data limit by 25th feb 10.15 pm. But yet my balance is deducted. Also there was no sms sent to me to inform about balance deduction. But customer are executive was adamant that i had crossed my 1 gb data limit. Then i asked customer care executive about the time i crossed the 1 gb data limit. So they said they dont have that information. I want to know who has that information. I was cheated and need to understand how and when my data got deducted.
I called for rasing the complaint and i was told complaint can not be taken for this.