Join Date: Nov 2017
Location: Northumberland. UK
That raises a few questions.
Does your car have 2 towbar switches, one lower drivers door and 2nd nearside tailgate ( oposite side to the lower and lock switches. If so then it's a factory fit as I don't think the dealers retrofit though I may be wrong.
Again if so I can think of only two possibilities, The car bumper has been replaced following a shunt or the cut out is there but out of alignment and towbar catches.
Easy to make the cut out yourself if none there as it's just 3mm plastic just cut carefully and finish off with a file, check first that there isn't a cut line marked, sometimes a moulded indent.
Does your car have keyless i.e. foot wave boot access in which case you'll need to be VERY careful not to cut the sensor wire behind the bumper.
The edge of the cut on my factory fit bumper is smooth so probably a special moulded part and is just a square cut however it's very difficult to measure accurately as you can see from the shape, the largest measutement is 470 mm.
What I suggest you do is get underneath and have someone operate the switch so you can see where it catches and just cut a little at a time until it works, you can see how far mine extends and the cut part is not visible unless to get down on hands and knees.
It's a 2017 250d AMG Line btw and my foot wave facility works whether the towbar is deployed or not.
Hope that's of help
GLC 250d AMG-line. Obsidian black, night pack. 20" wheels, premium plus, 360 cameras, Park pilot, intelligent lights, electric towbar. running boards. mudflaps