Ask for settlement amount and paid it

I spoke to a gentleman last week and I ask him to please give me a settlement amount. He said he will give me 30% discount and it must be paid within 7 days. I went the same day and transferred R5900, the amount he gave me into my RCS account. I ask him to sent me a letter stating that I finished with the account and he promised me that he will. He phoned me the next day and sms me with the e-mail and said I must fax the proof of payment to a Leigh-ann which I did. Now this week I received an e-mail asking me for the balance. I tried sending them e-mails and phoning them and no one is returning my e-mails or calls. If I do not get a response I will take this further to the Banking Ombudsman.