duìfāng rúguǒ zhǐ shì diànyuán, yě bù yīdìng yǒu quánxiàn ràng nǐ yòng nèibù cèsuǒ

对方如果只是店员，也不一定有权限让你用内部厕所。

If the other person is just a store clerk, they may not have the authority to let you use the staff restroom.