Identified on Caller ID as Nationwide Credit but it may be a contract company representing them.
Extrapolating from other posts concerning Nationwide, they seem to be VERY aggressive in assuring on-time payment. They dun on or immediately after the due date. They don't wait for the delinquent date. Remember, even if you have arranged auto pay for your due date, the payment won't clear until some time later (often about 10 days). Nationwide seems to have an automated system which makes "robo" calls to clients whose accounts show no payment has been made by the due date. In other words, they expect you to pay early. They also make these calls from different numbers. I am guessing that they contract with various service providers and that these contracts change over time so that your account migrates from one number to another. We get calls from three (3) numbers right now - 877-870-8888, 877-698-9400, and 571-499-4432. Very annoying.
But, other than being extremely annoying they seem harmless. As always, make the best deal you can. Don't make yourself unhappy by fretting too much about it. You can't fix it and It won't go away.