internet speed has never been what I pay for

Hello all. I just wanted to see what you think about this. My internet speed has never been what I pay for. I pay for 30 Mbps and only get 20 to 21 Mbps, and it never reached 30, never!. I call them and they say 21 is reasonable. Well, the way I look at it that’s a 33% reductions and not that’s reasonable. What do you think? Thanks