slow fibre / slow streaming paying for faster fibre

I am paying for the FASTER FIBRE and getting speeds of 3.46mbs, at the lowest I should be getting is 25mbs, it should really be connecting at 45mbs + (which I got when I first had broadband with TT, now a few months in, and my speeds have dropped!!!!) I am getting on average 8mbs to 15mbs which is terrible! and right now it is at 3.46mbs ... i can't stream anything!  I have tried direct using ethernet cable, and wifi. I find myself rebooting the rooter every 2 days just to try and get a good speed! this is not really acceptable. help!