Stop spam calls

Person claimed to be from utilita and had urgent information about my account but wouldn't give me any idea about what it was. I asked them to write to me they said they had but I've not recieved anything from them in last two months so said resend the letter then please. I'm not giving out my personal details for unsolicited call with no inkling of what its about he said to get that I had to go through security. I wasn't buying it. Also mentioned calling about my gas and electricity account but