Threatening me over the phone

Today 11 July 2015 at 10:26 I receive a phone call from a guy phoning from a 021 landline number from Discovery Health telling me I owe them money because I spent too much money for being admitted to hospital for 6 hours and did not have enough savings and withdrew my membership before 4 months. I responded by saying that it is fine I will pay the money if he can tell me how much is outstanding. He responds by saying \you will pay today or I Will hand you over to debt collecters". I have not received any invoice or notification of the amount owed to Discovery and was not even given a chance to explain that. """