It looks as though your feet are constantly slipping around inside your boots - the combination of pressure from standing, the friction and the hardness of the boots is creating the calluses.
Don't overfile them; that causes more damage and encourages even more callus formation.
You could make an appointment with a Podiatrist privately, as they can remove more without causing damage.
However, right now, you need to protect them.
Have a nice bath and gently pat your feet dry. Apply a good covering of a high urea foot cream and put on socks after you've sat for a while (for your own safety when you get up).
Hopefully, you've got a couple of days off now. Spend the time being gentle on your feet (cream at night) and then on the last night, rather than hacking away at them again, just use a rough towel to rub a little more of the callus off, reapplying the cream.
Turning to your boots, you probably need insoles with an arch support, as they help stop your foot sliding around. If the callusing is appearing on the sides, it's possible that you actually need a larger size for the width at the toes to go with the arch support/heel cup and then to tie your laces in a way that means your heel stays securely at the back instead of sliding forward and jamming into the sides.
I find that hiking/mountaineering/outdoor sports socks are better, as they wick away sweat rather than leave you with damp feet like cotton does and are often cushioned whilst reducing friction. They can be expensive, but I think it's worth it.