Call waiting removal

I have been on the phone and on chat with several different agents over the course of the last 4 days. I keep calling to get the call waiting removed from my phone line with no success. Every time I call or chat with an agent, they tell me the call waiting has been removed, and to give it a couple of hours. Needless to say, 4 days later and the call waiting has still not been removed from the phone line. Can someone PLEASE help me with this?? Thank you in advance!!