One criticism of the educational system (at least in north America) I have is that labs are generally taught in a cookbook fashion. Students read the manual, perform steps one through twenty two, write up their results and hand in a report for grading. Carnivroar, I suspect that you've come through a system like this.
Then, when you get into your senior lab, your instructions are purposefully vague and you're left out in the cold, wondering what to do.
Many schools keep the lab instructions purposefully vague because the point is that for a senior course, you really should be setting up the experiment yourself. That's not very fair when up until this point you've been repeatedly rewarded for avoiding any deviations from instructions.
It's no wonder you're developing a dislike for the course. I think a lot of students experience this kind of frustration. You should make sure that you give critical (but constructive) feedback to your department on it.
The other issue of course is the basic struggle with getting things to work - figuring out equipment you're not familiar with or that may or may not be in working condition, accounting for phenomena that aren't expected in the theory, etc. I would argue that you're actually learning a lot in such situations. Even the patience for dealing with things that don't work the way you expect them to is a valuable skill.
And at the end of the day, it's one course. Get as much as you can out of it. Don't make up data. And at the very least you've learned that you're really not cut out for experimental work. It's better to learn that now than two years into a PhD.