Is your 5-10Mbps speed based on running speedtest.net with an Ethernet connected computer or are you using a wireless connection?
If wireless, you need to check your wired speed and then troubleshoot your wireless network. Two different issues that are not clear from your initial post (although your tags indicate that you may be having a wireless issue).
If you are having a speed issue with only the wireless, I would start by downloading and running the free version of inSSIDer, a wireless analyzer from
HERE. Could well just be interference that needs some wireless adjustments. If it is a slow wired connection, you will need ATT to fix that.