I have a very simple solution for maintaining Monthly Average Balance for my HDFC account.
I have prepared Excel sheet in which I enter daily balance for that day. (although I don't do it daily, I enter amount weekly or in 10 days). I have table created with "date - Amount". Then applied formula to get total of amount for all days, and in another cell have Average formula for "Total amount / number of days" in that month. This Average should never go below 10000 at end of month. If it is below 10000, I deposit amount needed to bring Average above 10000 🙂
Though best option I found out is deposit large amount in beginning of month, so by end of month even if Account balance reaches 1000~2000, still my MAB remains above 10000.