We've been have the same problem. I finally was able to talk with someone and got information. The 712 945 0164 is a direct dial number, so you can't call them back. The caller is from National Union Fire Insurance Co in Pittsburg, PA. In our case, they were authorized by Homecomings Financial, a mortgage company to call us. The direct dial number for Natl Union (or the 712-945-0164 no.) is 800-781-8280. They will put you on the Do Not Call List if you request it.
FOR AT LEAST THE PAST 3 WEEKS RECEIVED SEVERAL CALLS PER DAY, IF YOU ANSWER THEY HANG UP, IF YOUR DON'T ANSWER THEY THEY NEVER LEAVE MESSAGE A ON THE ANSWERING MACHINE, THEY HANG UP.