In reply to Andypeak:
At one point a physio told me I needed arch support insert and some slight lift under my heel. I was able to buy not too expensive inserts then use the shoe's existing insoles as a stencil and scissors to cut the insoles to correct size for my shoe. In my case I removed the front of the insert completely so it was only heel and arch for me.
At no point did it cost me hundreds of pounds for custom orthotics, but my situation will be different to yours, but explore the options you may have, it might not be only the expensive stuff!
(As an aside, in my case I later saw a podiatrist who drew lines on my feet, ankles and lower legs with a biro and ruler and got me standing on a big wooden wedge in different positions and concluded I shouldn't have inserts or motion control trainers but needed to fix tight calves! 🤣 Amazing how 2 people can totally contradict each other. Turned out the podiatrist was was right)