I did look for info about your modem but I just can't find anything helpful....can you give me a model number, that might help

Do you know if it's a modem or a modem-router? If you have info at home (manual etc) have a look & see. You may have a firewall within your modem & that could be why you're seeing the firewall icon. Just remember though, that even if you can port forward & get rid of the firewall icon, if TalkTalk are shaping it's not going to help your speed much if at all.

One of the threads in that very first link I gave you has info about what hours shaping takes place. Have you tried downloading outside peak times to see if speeds improve?

my modem-router is R-ADSL-C4-2 with a brand name called Dynamode
since last my post i have changed the way my computer connects from usb2
to a network card, as a result i now have a link speed of 100Mbps with
networking at 0.07%-0.44% and a max of 0.5%.
when downloading my rate is 25kb/s-40kb/s and a max of 60kb/s
even with 11 hosts.
If you can use network manger (Ctrl + Alt +Delete) then click networking tab
what is your networking %