Harassing calls

I am so sick and tired of being harassed by ABSA Bank. I don't know how many calls I have received offering me a credit card or personal loan. I have never been a client of this Bank and never will be so why is it so difficult for them to take a hint that I am not interested. They waste my time and I make sure to make it very clear to who ever is calling me to take my details off their system. I wonder where they get my details from as I have never banked with them in my life? This is my last warning. Get a grip on your sales department and stop trying to force your products on people that made it clear 10 calls ago that they are NOT INTERESTED !!!