Tried to jump my car myself and failed, what am I doing wrong?

Spent half an hour this morning trying to jump my car with a mate's car and got absolutely nowhere. Connected everything, waited a few minutes, tried to start and nothing, just the same clicking. We checked the connections twice and they seemed fine. Now I'm wondering if the battery is so far gone that a jump won't help, or if we did something wrong with the order. I've been looking at Professional car battery jumpstart near Business Bay options because at this point I'd rather pay someone who knows what they're doing than waste another morning. My question is whether a completely dead battery can even be jumped or if there's a point where it's just too far gone. Also does the size of the donor car matter, because my mate has a small hatchback and mine's an SUV, and I'm wondering if that's why it didn't work.