All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon Prophet Mohammad and upon all his family and companions.
The fundamental principle is that the price in a sale contract is binding based on what the two contracting parties have mutually agreed upon at the time of the contract. Allah the Almighty says [what means]: "O you who have believed, do not consume one another's wealth unjustly but only [in lawful] business by mutual consent." [Surah An-Nisa'/29].
Upon examining the details of the question, the sale was concluded for the price agreed upon by the contracting parties themselves. The misrepresentation that came from the intermediary does not invalidate the contract, provided the contract was signed directly between the owner and the buyer. This is because the buyer had the opportunity to verify from the seller, at the time of the contract, the actual price he was requesting.
In conclusion, the sale contract is valid for the price upon which the contracting parties agreed. The seller is not obligated to return any portion of the price, unless the intermediary committed fraud against the company director. In that case, the director has the right to reclaim the 100,000 dinars from the seller. And Allah the Almighty knows best.