Want to upgrade to higher internet speed!!!

The tech that installed my "Max Plus" internet was amazingly helpful. He said that I could upgrade to 45Mbps speeds, but when I initiated a chat to do so the lady said that was the highest available. I contacted the tech to relay what she said and he was dumbfounded and extremely adamant about me being able to get much higher speeds, and even confirmed this with his boss. My question is why is it saying that I can't through the automated and chat support systems. I havent called because I have social anxiety disorder and fear doing so, as stupid as that probabally sounds to most reading this... Thanks in advance for any help!!!