Why was i sold x2 gigabit when those speeds aren't available in my neighborhood

I was upsold on the Xfinity X2 Gigabit package quite a while ago. My uploads are consistently at 49 mbps and my downloads at 37.  I have been asking for an explanation as to why my numbers are so low for quite sometime. Techs have been sent out and I am told it was performing optimally.  My son came home from college and explained to me that I am nowhere near 2000 gigabits, and that much was way, way overkill to begin with.  Then I spoke to some neighbors who are much better versed in this and they tell me that those speeds aren't even possible in our neighborhood due tot he age of the infrastructure.  Why am I being charged for a service that isn't even available in my neighborhood? And then, being told by your techs that everything is performing at the highest speeds.  I find that to be very deceptive.