It is recommended to communicate with each other. In addition, it depends on whether there is such a convenient agreement in your intermediary contract and house sales contract. If not, there is no mandatory provision by law. You can also contact the bank yourself and choose a more affordable bank to apply for a loan. Generally speaking, it is more convenient and quick for an intermediary and a bank to apply for a mortgage, but the intermediary generally has a price difference. As for whether the owner must cooperate, you can stipulate in the contract that, according to the general situation, the seller has incidental obligations, including cooperating with the buyer to handle relevant procedures.