What exercises do you do for your rear delts and upper back because I have been doing Bent-over dumbbell rear delt flyes and find them almost impossible with super light weight and have not got any better at them. The equipment I have is a squat rack, bench, olympic barbell, olympic dumbells, EZ curl bar and a beam for pullups.

Any help wpould be greatly appreciated as I am getting really annoyed with this exercise

are you using correct form? that's always a place to start. If you can, videotape yourself doing the exercises, post it on youtube and put the link up here.

That is an extremely small muscle and will never get very strong. Done with proper form you will never be able to do a lot of weight on that exercise. In fact this is one of the few exercises that is best done on a machine if you have access to the machine. There are some other exercises you can try to supplement the flyes, like external rotations, chest pulls with a band or spring apparatus, etc.

I think i'm using correct form although if I put more weight on then it decreases my ROM loads so I have had it the same for ages. The machine is easier but I don't really have access to one. Will the exercise where you hold a barbell and lift it up to your face help my rear delts?

Try some Shrugs. Those are really easy to do and a great exercise for the upper traps.