I received a call from the same number today. I'm not sure who it is from, but I know it's some sort of bill collector. The only outstanding bill I have right now is from Orchard Bank, so I suspect that it is them or some agency acting on their behalf.
Don't bother to answere the phone they are a bill collector for American Express. Very rude and unprofessional. They will harrass you night and day. Don't make the same mistake I did. Seek legal advice to handle the situation.