Here's a tip, answer the phone in a heavy foreign accent and say your houesitter or housekeeper. for example: " Allo, I sarry kant understand , No home, sanks syou, no call no more!" then swiftly hang up. I've tried this a few times, You might as well have fun with it. They want you to get frustrated. Their job is to report back to the company that they have met their quota of phone calls and how many calls were answered. So by answering the phone in this way, may be a solution. I have answered the phone in this heavy accent way every day for a week and they have completely stopped calling for two months now. (knock on wood). Good Luck!, and Have fun with it!
P.S. It is RCI Timeshare company, We do own many timeshares through RCI and Interval International. All they want to do is sell you more and more timeshare.