False info in offer to purchase contract

I bought a property in Ballito. An OTP was signed which stated there were registered up to date plans for the property. About 2 years after the sale I tried to get hold of the plans, the municipality rep**** that there are no registered up to date plans. I also contacted the previous owner who said Sotheby's was fully aware that there were no registered up to date plans. Sotheby's reply is that it's not their problem