Sokolov concluded a contract with a real estate agency

Sokolov concluded a contract with the real estate agency, under which the agency undertook to select for him a three-room apartment located in a brick house next to the metro station. Sokolov made an advance payment in the amount of 100% of the apartment´s value and paid for the agency services, which constitute 7% of the apartment price. All funds were transferred to the representative of the agency and placed in the safe, one key from which they transferred to Sokolov, and the second was at the agency’s administrator.
When an apartment suitable for Sokolov was found, it turned out that its value was 60% of the amount received by the agency from Sokolov. Sokolov, after registering an apartment in his own name, demanded that the agency return the difference between the remuneration actually paid and the amount due to the agency. The representative of the agency said that an agency agreement was concluded between the agency and Sokolov, under which the agency acted on behalf and at the expense of Sokolov in the selection and design of the apartment. The price of this contract is 7% of the value of the apartment. Responsibility for violation of the obligations assumed by this agreement is not provided, especially since the agency, having found a cheaper apartment for Sokolov, fulfilled its obligations under the agreement with the greatest benefit for the client. Sokolov sought the advice of a lawyer.
Questions to the problem:
1. What advice should I give to Sokolov?
2. Prepare a plan of necessary measures to protect the interests of Sokolov.