Hi Rafales,
ACT services are very reliable and are pioneer in speeds. Where are you located? I have been ACT user from 2012 in Bangalore and Hyderabad.
Barring one instance in Hyderabad of downtime, I have never faced severe service issues. As far as FUP is concerned, they have usage listed in their home page as well you can ask for itemized usage. No discrepancy so far reported.
Cheers!