The new property management company has not signed a contract with the owner.

Legal analysis: you can't refuse to pay the service fee. Regarding the legal consequences of signing a written property service contract in the future, according to the relevant provisions of our country, if the parties have not concluded a contract in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established. In other words, the illegal form of the contract does not necessarily lead to the invalidity of the contract. If the property management enterprise has actually performed the service and the owner has accepted it, the owner cannot refuse to pay the increased service fee.

Legal basis: Article 490 of the Civil Code of People's Republic of China (PRC). If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it. A contract shall be concluded in written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.