Gigablast issue

Hi guys, so i just upgraded my internet to the Cox gigablast service and i am suppose to be getting 1000 down/ 35 up. After the cox agent came to install the equipment and hook up the internet i am only getting around 100 down/ 5 up and even sometimes the internet drops below 1 down/ 1 up. I have no idea what the issue is because i have their 3.1 modem as well as a good router (NetGear NightHawk). I called for an agent to come out for a second time and this issue is still not resolved. The agent told me that it could possibly be my tap box outside, and that it could take up to 2 weeks to get a maintenance out here to fix it. I had the ultimate package before upgrading to the gigablast which was (300 down/35 up) and i had no issue with that internet. the problems only started to rise once i upgraded to gigablast  

I am a Youtube content creator/ twitch streamer, so having this bad of speeds is really affecting me. If anyone knows whats wrong please let me know ASAP. Thank you guys!