Hi Fabricio (are you brazilian too?)
I supose that you are using mikrotik that same way i do. Are you a wISP?
I currently use simple queue to control the bandwidth of my customers, for example:
open the terminal console and type:
queue simple <enter>
add name="Apto444" target-addresses=10.10.4.44/32 dst-address=0.0.0.0/0 interface=ether2 parent=none priority=8 queue=default/default limit-at=64000/128000 max-limit=64000/128000 burst-limit=128000/192000 burst-threshold=32000/32000 burst-time=8s/8s total-queue=default
doing this, open the winbox interface on queues, and you will see and undestand how to create this by winbox.
you can use limit-at and max-limit with same value.
the bust parameter is optional, but it is a good ideia cause the web navigation will be improved and your customer will be dazzle.