The drain hose on this appliance is in 2 parts.
Unplug the appliance and take the top and rear panels off.
At the rear, left you'll see a plastic container with the external and internal drain hoses attached to it.
Take the clips off the hose end and twist the hose whilst pulling on it to get it off the spigot. It helps if you slip a thin screwdriver between the hose and spigot to break the seal.
If you are changing the internal hose, it's the same idea except you have to take off the pump end too. You can do this from the rear, although it's a bit of a stretch.
You can see the exploded view of your appliance at www.bosch-eshop.com
Click on the parts, search on your model number and open the document relevant to your appliance.
Click here for the exploded view
Hope this is of some help
Let me know how it goes or if you need more help.
Sorry, the link to the exploded view doesn't work.
It takes you to Bosch but you have to manually search.
It's still the same thing, disconnect the hoses from the bottle on the rear of the appliance.
The new internal hose comes with a new bottle.
Disconnect the internal hose from the pump on the front of the appliance.
Fit the new pipe and bottle, connect the external hose to the bottle and it's changed.
However, you need to make sure where it's leaking from.
Take the rear panel off, put a little water into the appliance and see where it runs out from.
Good luck with it
The side panels don't come off.
Open the door and take off the seal retaining ring, you'll need to dig this out of the seal.
Peel the seal off the front panel.
Take the screws out of the door lock.
Take out the dispenser and remove the screws revealed.
Take the panel under the door off.
Take the screws revealed out.
Push the front panel down and lift it off.
If it's still held in place you'll need to take the facia panel off to get to a hidden screw.
Reassembly is the reverse of the strip down.
To refit the door lock, reach in through the port hole and fit into place, screw it in then fit the seal.
Hope this helps
Let me know how it goes.