The connector should be soldered to the wire. If it breaks off, just heat the connector until the old solder flows, insert a stripped section of wire, add some fresh solder and allow to cool. Then reassemble. Many Mercedes electrical connectors are of this type.
It actually looks like you don't have the connector. It looks like someone just wrapped some bare wire around the terminal, put the cap back on and hoped for the best. You can find these connectors almost anywhere on the car. Junk yard is probably the best option.