If the machine is under warranty (1 year) then it is better to contact Zanussi and get it repaired under warranty.
Opening the appliance will void off warranty.
However, if it is not under warranty then please try this:
You will have to unplug the appliance and pull it out.
Then remove the top off and locate the pressure switch with thin hose attached to it.
Remove this hose and blow through it, make sure it is not clogged.
Then with the top off the appliance, locate the hoses going into dispenser and clean them completely.
Also clean the hose that goes from dispenser to the drum, make sure it is not clogged.
This VIDEO will give you an idea on how it’s done.
Reconnect everything and plug it back, problem should be solved.
Please let me know how it goes.