Airtel — debit for my account is not allowed, i. e. transaction failure

I recently deposited an amount of rs 309 in my airtel wallet. Now when i try to do any transactions from it a notice appears and says "debit for this account is not allowed".
Cc from airtel what does it mean. Quite frankly i care less about what it means. I want you people to kindly solve my problem because i got other things to do too, i have stuck here my data plans are about to end. Please solve this problem as soon as possible.