I agree it was a most unhelpful answer. A few seconds searching shows the maximum height of humps should be 100mm and the ground clearance of a Touran is 155mm. So I'd suggest going back to the offending hump (there must have been a hell of a crunch) and try to measure its height. Then check that nothing is wrong with suspension or mountings to cause the engine to sag. Nothing to lose by putting in a claim, apart from a small claims court fee if you eventually have to go there and costs if you lose.

Other than a driver going to fast or braking at the wrong time and the front/rear of the car dropping at the wrong time, sometimes the problem is made worse or caused by the road sinking just before/after the hump, often because of vehicles are braking/accelerating and thus more force is being applied to the road. This means the difference in height between the lowest point right before the speed hump and the top is increased.

I've seen this locally many times and reported the fault to the council, and generally they are repaired, although mostly with 'fill in' repairs that don't last that long, especially in winter.

A quick google gives a wide range of values for ground clearance, the lowest being 101 mm.