Yes, Spain lost Gibraltar in a war. Pretty much every border was decided by war, so why is that border different? ("we had it a long time" isn't a difference.)
Yes, Gibraltar is dependent on Spain for services. As I pointed out, that's a tool for changing the border. (Blockades are an act of war, so that would be "at gunpoint.")
However, that dependence isn't an argument that the border is "wrong".