Isp throttling dsl services?

For a little anonymity I won't say which company I work for but I will say it is dsl based service. I have spent the morning working for a business customer trying to resolve slow surf issues. I changed ports in the central office. I swapped routers. I tried several different terminals with and without the others connected and I never surfed over 1meg on a 6 meg circuit. I had the dslam checked and the username verified for not being on a static ip or anything else that could slow them down. It wasn't until I swapped the username and password out for my personal one that I was able to surf at the right rate. I then put the customers info back in and the problem remained corrected. this isp offers dsl and their next generation service which is ptm vs atm. So my question, could/would there be the possibility that these older platform users are being throttled back in a bid to convince them to upgrade to the other service offered? The only characteristics that changed on the whole circuit with the username swap was that the ip address pulled was from a different bank.

Actual it could also be a older ip bank router they are going through. Or the router/switch needs replced.

Tracert both accounts and check where the hang up is.
Actually we had that here after they move the servers from N.J. to California. Found some routers/switches that were glitched.

I received a company email last week stating the legacy ATM dsl services are being throttled. It's in an effort to persuade people to leave the older technology and move over to the new PTM service we provide. It details that there are ways that a person can have the throttle removed. Also if a person is pushed over to the other service and demands their old service back they can have it. This is only being done with residential customers who serve directly out of a central office. FTTN, FTTP, and other remote solutions are not being affected by this yet. I figure it would take too much time to go to each of them and set up throttles. At least for now....

When you reboot the modem, the first thing it does is to get the new firmware which holds the limits. Some can be forced to reboot from the IP end thus enabling the new limits.
Seen the forced reboot by cable and DSL companies.