The bathroom looks at the leaking property downstairs and says that the waterproof layer is broken, so let the upstairs repair it yourself. Can the property management company handle the merger?

It is not his responsibility for the property management company not to handle it. Look at your signature, renovation contract. The warranty period of concealed works shall be 6 years. It hasn't passed the warranty period. It is his responsibility to find a decoration company to decorate you. If he's still here, I'll fix it for you, but I'm afraid the decoration company will go bankrupt and no one can be found. If the waterproof layer is broken, it must be completely redone. Remove all the floor tiles and some wall tiles. The tile money should also be accompanied by the decoration company, because if you have not passed the warranty period, it is his responsibility.