Has anyone on here suffered Plantar Fasciitis, if so what methods have you used successfully?

Yes, I first had it in my 40's---25 years ago; and only one bout with it since.

Here's a summary of what I know about it---redacted from internet sources that summarize what I know.  And I'm including a few personal comments.

It's an inflammation of a thick band of tissue that connects the heel bone to the toes.  It's Very common---more than 3 million US cases per year. It's usually self-treatable; self-diagnosable, and lab tests or imaging rarely required.

There are bio-mechanical causes relating to the shape of the foot and the height of the arch, but 90% (yes 90 %) of the cases are due to tight muscles in the back of the leg which limits the flexibility of the foot and places undue stress upon the fascia.

If your doctor agrees that the most likely cause is muscle tightness in your partner's case, then I would recommend the heel cushions (they are a type of orthotic---but cheap as orthotics go) for immediate relief and stretching to eliminate the problem as a good first attempt at remediation.  (The doctor actually gave me a pair at my first visit and then sent me to physical therapy to learn and do the stretches.)

Your partner is going to have to take some action to get well. Plantar fasciitis is basically the result of ignoring required maintenance of our body and it won't go away unless we do the required repairs.

For immediate relief, try a pair of Bauerfeind ViscoSpot, Size - 2

https://www.amazon.com/Bauerfeind-ViscoSpot-Size-2/dp/B007GBBHEE

Then have him start doing some stretching exercises for the muscles in the back of his legs for about 3 weeks.  Here's a site for the stretches  http://smiweb.org/wp-content/uploads/2012/04/plantar.pdf

I would only do the Hamstring Rotational Stretch & the Calf Stretch and save the rest of the pdf for later with the doctor's guidance.

Good luck.