Extremely slow speeds in my neighborhood

I live in a pretty dense neighborhood (condos) and my Gigablast internet regularly drops to 3-5Mbps during peak hours. I understand that speeds aren't guaranteed but this just seems pretty much beyond acceptable.  0.3% of the speed I am paying for. When can I expect Cox to increase the available bandwidth here? How do I report this so that it is addressed?

Also, Even during non peak hours (5 or 6am) my maximum dl speed is on average 3-400Mbps. I have on one random test reached 780 - but that was only once in the last 4 months or so, why am I paying you more for the same speed I had with your Ultimate package???