Therefore, it is understandable and acceptable to charge some necessary fees appropriately after the system is installed.
As for Jindun Company, it must be a supplier of security system installation and maintenance that works closely with the police station. 600 yuan, who received you, obviously has set the corresponding installation fee and maintenance fee. If you have any objection to this fee, you can consult or complain to the police station or the legal department of the public security organ at the next higher level; Of course, the probability of accepting or handling similar complaints is very low. It is estimated that 600 yuan signed a text similar to "Installation and Maintenance Agreement" with you. Just like the "broadband" installation agreement signed with the telecommunications sector, there is little or no room for negotiation, but you still have to continue to sign.
Calculate an account. If you can figure it out, sign it. Otherwise, it may not be a good thing to toss and turn, but you still have to consult the branch. At this time, the police station will not take any frequent measures to take care of you.