Giardia - Help needed!

My 12 week old bernedoodle puppy has Giardia. I’m pretty convinced she’s had it the entire time we’ve owned her but the vet has only just done a stool sample to confirm it (I’m a first time dog owner so didn’t know enough to push). She’s on day 4 of panacur with no improvement (constant diarrhoea with blood and mucus) and now the vet wants to do another three day stool sample before they’ll prescribe further treatment.
They’ve given no guidance on how to stop her getting it again as she has had diarrhoea over every inch of the garden which can’t be helped but I don’t know what I need to be doing in or outside the house.
HELP!!!

How does she seem in herself? Is she eating and drinking OK? I've no medical advice to offer, but I wonder if it's worth trying to arrange to speak to your vet on the phone to ask some specific questions - arm yourself with a written list, and make sure you get a clear answer to each one.

She is super playful, eating well and drinking well so all good on that front. I called the vet and the only advice they gave was to wash her feet when she comes in from the garden which I’m doing with wipes but was hoping for something more detailed as there is so much conflicting information online about what I should do with regards to disinfecting the garden/house.

I'd have thought that the Centers for Disease Control and Prevention would be a reliable source: About Giardia and Pets

In your position, I think I'd do as much as I can from their recommendations, but not worry if I can't clean everything - he should recover just fine, and you're unlikely to catch it.

My dog had giardia aground the same age. It took a while to go and the vet did say it takes a few courses for it to be cured. Think it took 3 courses in the end.