United States Medical Department - Daniel DeSouza (supposedly) Harassing Calls Houston Texas

I've received several calls over the last 6 months or so from callers asking medical questions and claiming they're from the United States Medical Department or a name similar. Today, the person, who had a thick Indian accent, called once and when I told him I wasn't interested and to remove me from their call list, he then proceeded to call back twice and harass me. I tried to ask for his name, location, and a telephone number to the main company, and he gave me what I'm assuming is a fake name (Daniel DeSouza), told me he was from the United States Medical Department in Houston Texas, and refused to give me a number unless I gave him information. I tried to ask to speak to his supervisor, and after being beligerant for several minutes, hung up. I tried to call the number back - (713) 972-3814 - and it says it's disconnected.