Caller: Possibly they work for Credit Corp

Credit Corp continually chase you for supposedly unpaid debts that they have purchased from a finance company for as little as 4c in every debt dollar you supposedly owe. So for a $1000 debt they have purchased for as little as $40.
Never ever ring them back as your credit 7 year blacklist will start again.
Your debt gets wiped after 7 years if you don't make any contact with them.
Block their number but they will continually ring you on other phone numbers that they have a rotation of hundreds of landlines & mobile phone numbers they use.
Rule of thumb is never answer any phone calls from people you don't know if they aren't in your address book.