So you are telling me that Cacti and Solarwinds are/have applications that manage bandwidth?? All these years I thought those were only for monitoring bandwidth utilization and that management requires some hardware/software combo.
Rotich, you can use pfSense to manage bandwidth. You install it on a hardware with at least two NICs and place it strategically on your network so that all traffic is passed through it. You of course need to configure the management bit yourself. pfSense is Free. You can also buy a pfSense appliance if you don't need to install it yourself.
Another option is one of the many Mikrotik routerboards available. You choose one that matches your needs and then configure it - or pay someone else to configure it for you.