Ghiardia and coccidia suck, but ghiardia is by far harder to get rid of in my experience. My old foster pup Juice almost died of coccidia before we got her into rescue--she was a skinny little mess. But it cleared up pretty easily.
Every dog I've gotten from the Baltimore City shelter so far has had ghiardia, and it seems like it never goes away. But eventually it does, I promise! I now get Drontal and metronidizole from my vet to treat it. I give the Drontal short term (usually just a couple of doses) then 10 days straight of metronidazole even if the dog seems to be improving. During that time, the dog also gets a very bland diet--boiled burger or chicken (white meat is best though pricey), yogurt, and a bit of boiled rice. Use the rice sparingly though--it tends to not digest well, especially in dogs with colitis and inflamed bowels.
During the time the dog has the parasite, resist the temptation to give raw--during this time, I've found, the dog is most susceptible to other bacterial infections of the gut and I really have had horrible experiences giving raw anything to dogs who already have intestinal issues. Don't give any treats like rawhide, pig's ears, cow ears, either--they'll make it worse and if they have bacteria in them, it'll attack the dog's digestive system too.
Very often ghiardia does come back. I had one dog who was on and off with it for almost 2 months, but finally we kicked it by just doing the same regimen over and over a few times.
They key is to get as much nutrients into the dog as you can, build the immune system, and hope the drugs can help the dog's body overcome the parasite. It's a bitch, and it sucks to see a dog going through so much bowel distress for so long, but in my experience, it does eventually clear up! Never tried the vaccine, though. Hope the Drontal helps and good luck!