Stuka,
First, with regard to the reps listening to your sales call, it would be good idea to post either a case number from a prior phone call or the serial number from your modem so the reps can locate your account. They may not be able to do so with your sign on info, so one of these two pieces of info will help. DO NOT POST your SAN (your account number), just a case number or the serial number.
Secondly, with regard to the speed tests, you should head to testmy.net, create an account, and run some tests under that account. Running the tests under an account you create will save the tests in one central location so they can easily be looked at. When running the tests, please make sure to use a single device connected directly to the modem with a LAN cable, NO ROUTER. Please be sure to use the 12MB manual size for download tests and the 2MB manual size for upload tests, though the download tests are the more important of the two. When you run a batch of tests, it's best to run three to five of them, and space the tests at least five minutes apart (so five tests would take at least 20 minutes). Also, if possible, it's best to run a batch of three to five tests a few times a day, preferably one batch in the morning, one in the afternoon and one in the evening. Again, though, that's not always possible, as we have to work and such. LOL.
When you've run some tests, you can post the URL of your results page. When signed in at testmy.net, click on "Results" at the top right of the page, and copy/paste the URL in the address bar of your Results Page into a post on here. Remember, though, you have to be signed in to the account you created when running the tests for them to be saved where you can easily see them. It's better than posting each individual test, and having them in a centralized location also allows patterns to be seen in the speeds, which can be very helpful in determining what the cause of the slow speeds are. The URL will look similar to the following, but with YOUR user name where it says "yourusername".
http://testmy.net/quickstats/[yourusername]
Good luck.