When the user's limit is breached, funds aren’t added to their ledgers (credits can be made up-to that specific limit, unless it's reversal transaction), and thus users are not debited. In case the users are debited, the payment gateway will initiate the reversal for funds back to the source account (Issuing bank).
For example, user added Rs. 7000 first and then tried adding Rs. 4000. The second transaction of adding Rs. 4000 will fail as it breaches the set limit for min KYC users.