Here's how to give them a dose of their own medicine.

Call back that number from an unlisted landline, follow the prompt.  At the end you will be asked to leave name, number and preferred schedule to meet them.  Give false name and number, and it is important to pick the earliest date.  Then they would have their reps/telemarketers listen to messages that are requesting early meetings - thus efficiently wasting their time and money as well - payback!!  I left them 4 messages 4 different names from the series Heroes :), earliest times.  Leave as many as you can, you dont have to wait for their sales pitch the second time around, just press 1, 1, and 3-digit code.