Such an obvous advice but thank you. I called ARC back and asked what they wanted; they were looking for somebody I don't know. Asked them to remove my phone number, was advised they would.
The automated message says the calls are coming from Accounts Recovery Corporation. Given that I have no outstanding or delinquent debts, I suspect it's a scam. This is how they try to get around the law in Canada which allows consumers to add their phone numbers to a "Do Not Call" list for telemarketers - they just "pretend" to be calling about a debt.