Misrepresentation on offer to purchase (OTP) resulting in financial loss of R30 500

I bought a 2019 Audi A4T FSI Stronic (B9) (35 TFSI) of engine no: CVN096700 from McChathy Audi Wonderboom on 27 Feb 2020 at an inflated vehicle price of R30 500 following a misrepresentation from the officials at the branch. They made me to sign the ABSA vehicle finance contract on the system without providing me with the OTP for me to confirm the details and when I asked why the amount was still high even after a deposit of R40 000 they said the OTP will be provided later and should it be less a refund will be processed to avoid reapplying for the loan. Upon receipt of OTP no. 116799*, it was confirmed that the vehicle price was R 430 500 Incl. VAT while the vehicle was offered to me for R 400 000 Incl. VAT, by McCarthy Audi Centre Arcadia as the vehicle had 60 894 km, however they insisted that I should buy from Wonderboom as there was a pre-approved contract from ABSA. I never signed the OTP as it was pure misrepresentation from the branch and the branch manager said she was not there when all this happened. Please assist so that I could get my refund of R30 500 back, as this is highly unacceptable behaviour and conduct.