I have a Peugeout 308. Sometimes when my car goes over small bumps I can here a noise in the back of the car to the left, somewhere between the door, door arch or even the top of the shelf near the back windscreen! It’s like a plastic sound as in a crisp snap like plastic on plastic! I have tried to rub wd40 on it and some other types of fluid but I can’t get rid of it! I’m not even convinced I have found where it’s coming from. Any advice please? its not the parcel shelf and I have emptied the boot, thanks!!