I added coolant GP's on my 05 Golf. Found used flange on ebay, and replaced some hoses to accomodate them. They are manually controlled using a momentary switch so I can turn them on individually. Two relays control them as well. My fuse box atop the battery does have an empty slot fpr a 50...
Had a rodent get trapped in my serpentine belt. I was lucky too that the loose belt did not do any harm. Happened in a busy intersection.
A squirrel had probably spent the night under my hood and managed to go for half of my commute before the belt popped off.
Try spraying penetrating oil around the dust boot. If that does not work you may need to replace the caliper. The local part store remans are not very reliable in my experience. idparts has new calipers that I have had good luck with both rears.
My fuel gauge also fluctuates at certain times; has always been this way. Replacement fuel pump did not change the needle movement.
The gauge is otherwise accurate. The needle will drop down and eventually come back up one or two hatch marks.