Harrasment Calls

It has been almost 5 years that I have requested an investigation be done on the debt they keep on calling me about. I have asked several agents to put notes on the file and give feedback on the matter. But I keep getting called to pay with no sort of feedback on the issue I raised a query on and asked to be investigated. I have asked to be taken off the call list until the matter is resolved but I am still being called every second day by different people and it truly frustrating.