after having tried and failed to replace my front brake pads today, I am hoping someone on here has some tips on how to proceed.

I changed the right hand side pads without a problem. The pin that holds the pads was a little bit stuck, but 2-3 small taps loosened it up nicely.

The left hand side has been nothing short of a nightmare.I have tried gentle tapping, some big hard whacks with a persuader, spraying WD40, applying heat ...
I cleaned all the exposed parts of the pin, because there was some rust. But to no avail, it is just stuck.

Does anyone have any bright or creative ideas on how to get it unstuck?

Hi Duibhcek, it sounds like you're doing all the right things already.
let the wd40 time to soak in,

perhaps try rotating the pin using a pair of vicegrips, gently though! small movements at first building up- then knock out with punch

worse case, remove the caliper, rest it on a solid surface- a vice would be good! now try the pin punch. a solid resting surface allows all the energy of the punch/hammer to be delivered where it can be more effective

when out a good clean with sand paper and a liberal coating with copper grease should see you sorted!

That Welsh soil certainly tested a few bikes! my problem is at the manufacture being checked to see why it failed, should know today if it's repairable.

I was on the WR in Wales
This is probably the result of the previous owner's treatment of the bike. I was expecting a bit of resistance, but after only 20k km it shouldn't be this stuck if it was properly taken care of.

I'll keep my fingers crossed for your shock.

Finally got it out!

loads of WD40, brake cleaner, patience and many, many hits of the persuader finally broke the little b*st*rd.

there's a crust of rust on the section of the pin that resides inside the brake caliper. And there was a puff of rust coming out when it finally came loose.

So I'll be thoroughly cleaning the pin with some sanding paper and greasing it up copiously. The caliper itself will get a thorough clean as well. Just to avoid similar problems in the future.