Well ACT may upgrade the speed automatically but the end result is barely different. Pretty much every evening the speed is < 500kbps (yes, bits) on my "75" Mbps plan. Only in the morning I get the advertised speed and that too only for torrent. Youtube or any website browsing feels like a worse than ADSL connection, same with direct files download from anywhere outside India. I liked it when they had 10/20Mbps speed which were available 24/7.
That depends on your isp. Not all ISPS are the same.