Harry saw an advertisement for an apartment for sale "off the plan" with "massive stamp duty savings". On Saturday Harry signed a Section 32 disclosure statement and a contract for sale, and paid 5%

Harry saw an advertisement for an apartment for sale "off the plan" with "massive stamp duty savings".  On Saturday Harry signed a Section 32 disclosure statement and a contract for sale, and paid 5% deposit.  On Wednesday following, Harry appointed you as his Conveyancer.  Special condition 100 of the contract required Harry to pay "up to 10% of additional construction costs if the construction was over the building budget".  The budget was not disclosed.  Harry, dismayed, wished he had never signed. Advise.