Retrofit the trunk socket of the Ford Tourneo Connect Model 2016

Hello together, since I have unfortunately not found out (some threads are already a bit older and without concrete solutions), I try my luck with you. With our 2 year old Ford Tourneo Connect the socket in the trunk was dispensed with. Enquiries at an authorized Ford workshop as well as directly at Ford did not bring the desired success. Only by the hint with the hidden line I found this and made an socket on it. Unfortunately missing (although ) the wiring up to the battery or fuse box. At the point where the fuse should come in for exactly this socket, there is only 1 pin (minus pole?), the main line stops somewhere. Therefore the socket broke and the fuse does not succeed. Ford signaled to me that you do not know (exactly) how the cable runs. Ford himself referred me to the workshop, there even threatened me at that time with the removal of the internal covering and that the fun nevertheless I have the feeling Ford has dispensed with this in a van quite important socket so that they can collect well during retrofitting. Also, assume here from different methods of the workshop. One is honest and/or has a clue, closes it briefly not so much, the other istvoder makes on ignorant takes the half car apart and makes a thick bill. Can please help me please? Thank you in advance. Many greetings