By giving them another queue with higher limits, or even letting them bypass queueing completely. Just bear in mind that bypassing queues for the traffic of these users will mean that the queues will not know about that traffic, so even the guaranteed rates in the queues may not be delivered. Normally, the sum of guaranteed rates should be lower or equal to the uplink bandwidth, maybe with some known overbooking ratio - it depends on your legislation how much you can cheat.