If you are running ADSL Max, you need to have the cable running from the Master Phone socket to the router from the first time you have your line activated. The line will then find it's optimum rate, by working off the attenuation/noise margin on the line. Once it's at that level, if you want to have it changed, you need to contact your ISP and ask them to put the line back into the Rate Adaptive Period.
If you've had your plugged into an extension cable from the master socket, and it's stablised at a lower rate, than that might be why you're only getting 2mb, rather than 8mb.
