Fone Yam at Pep

I took am contract to the company called Fone Yam, in 2023 November, so they said I have to paid a deposit of plus minus 1000 rand I did, and they told me after 7 days I have to pay the initial installment of R275 I did, at the end of November the installment starts, according with my calculations and according with contract I supposed to finish end of November 2024, November 2024 they send me a message reminding of the installment I paid , December I got a message again I paid, now I email them I asked exactly how many month still they said I still have another 2 months more , meaning that their Contract is 15 months