Hi there,
I was excited to remove some really old taps with a mixer (https://www.bunnings.com.au/estilo-chrome-pin-lever-basin-mixer-wels-4-star-7-5l-min_p5003308). I definitely got the mixer working which is great, but the old tap handles - which I intended to replace with cover plates (https://www.bunnings.com.au/kinetic-white-basin-cover-plate_p4920336) - are stuck!

The way it is now is that all 3 holes are in the way of my mixer + cover plates 🙃

To be honest, I had actually loosened the nuts that joined the tap spindles with the middle connector part which sits under the spout (under the middle hole). Looking back, I probably should've kept them on before I went about trying to remove the nut on the spindles (above the basin). So now it looks like this underneath.

Anyway I tried loosening the spindles in various ways, and I'm worried I might've already ruined the nut (originally used an adjustable wrench in a desperate manner instead of a proper tap spanner). So I've come to the workshop for some advice. If it comes to it, I'll call a professional but otherwise, thanks in advance for your help!!