Water coming in rear next to amp on offside and also drivers side rear in boot behind flaps were lights are. All ready had to replace the amp due to water damage. Please please any clue. I got the car in my father's will I don't think he knew anything

[Guvnor]

Water coming in the rear we're the amp is on offside also drivers side the wiring loom soaking wet. Please please any ideas this was my late father's and its soaking wet both sides, I'm sure he new nothing about this.