my neff dishwasher runs for long periods 4-5 hours and the water is cold?

I have a 2 year old integrated NEFF dishwasher
S5453X1CB/56 FD 8412

Over the last 2 days I noticed that despite being left to run overnight the machine still had not completed its cycle overnight.
.

I have tried to reset but the water never runs hot.

Please can you advise what steps I should take before calling an engineer and give me a diagnosis of likely problems with estimated costs for repair.

elaine.jenkinsaprees@hotmail.co.uk

How much will a repair cost