Ok
Get a small flat bladed screwdriver and a bit of cloth or a rag.
Put the cloth or rag over the tip of the screwdriver to avoid marking the trim
Insert the screwdriver into the top of the panel and then prise it out like so (using the fingers of your other hand to help):
Now pull the panel outwards...
Turn the panel so that the triangle button faces the roof of the car to get at the connector.
Press and hold the tab on the connector down (in the below picture my thumb is on the tab holding it down) and then pull the plug apart from the switch
Feed the now disconnected switch through the front to remove it:
Now on eBay there are some sellers selling the switch plus the triangle plate, and others just selling the switch and you need to re-use your old triangle plate. If you need to reuse your old triangle plate, just pull it off the old switch by hand:
Then you can just push it on the new switch.
To fit the new switch just feed it through the fascia plate, connect it up at the back, and press the panel (that you prised off with the screwdriver) back in to place
Easy