I had my last sales call come through last Tuesday (16th Feb) and had changed my contact preferences at end of January. What makes it more frustrating is your sales team won't be frank about the reason for the call:
"Is this a sales call?"
"We're calling to improve your service"
"I'm at work and don't have time for a sales call, is this a sales call?"
"We'd like to offer you upgrades to your account"
etc......