Here is my situation:

Somebody is trying to overload my server with requests.

To my site are coming thousands of requests from approx 20 IPs that keep changing. The requests are "legitimate" requesting HTML page. Problem is that this consumes LOTS of my bandwidth I pay for.

Banning the IPs didnt solve anything, they just changed.

I am looking for a mod/solution that would allow me to limit number of requests per IP over period of time (not at same time, tried that with mod_limitipconn, didnt change anything) or even better, allow me to limit volume of data per user over period of time.

I tried mod_throttle however it is no longer being supported and the ThrottleClientIP is known to cause the server to lock up on heavy load.

I need a solution that wouldnt be too resource-consuming, since we talking about millions of hits per day.