Without the information requested in my previous response, I can only give you a general answer, but I hope this helps.
These type of issues usually occur due to water pressure issue.
You may try a rinse/spin only program and see how it goes.
If that works fine then please try this:
You will have to unplug the appliance and pull it out.
Then remove the top off the appliance and locate the pressure switch with thin hose attached to it.
Now, 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.
Then try again however, if it stops again then try a cold wash only program, if the appliance completes the program then I am afraid the heater is faulty and will need replacement.
I hope this helps, please do not hesitate to ask any follow up questions.
I hope you enjoyed your experience with justanswer.co.uk today.
Have a wonderful evening.