Ballon Payment

I bought a car at Omars in witbank last week Thursday 22 October, before I the signed contract I asked a sales man about residual 'he said to me there's no balloon payment, I was happy to hear that. So they delivered the car and I signed a contract but they didn't give me a copy due the fact that it was late for us to make copies, then Tuesday the 27 October I asked them to forward the documents , they only forwarded 2 pages, and when I read it I found out that there is a balloon payment, and when I try to call the sales person their phones are off. I'm not happy at all about their service .They should have explained it me and what makes me angry I asked them several times why they didn't come clean??. Firstly it was the monthly payment they said to me I will pay R2600 when I checked the contract the time I signed it was R3040, they said to me the bank added some of the money so I decided to sign it. But now am not happy about this balloon payment. Can you please assist with this.