I have a Neff dishwasher,Water gets lukewarm after 2-3 hrs,  runs for up to 6hrs
	
	
		I noticed that the dish washer was running for a long time. Tried it during the day and it took at least 6 hrs at 50c. Water is cold for a couple of hrs then heats to lukewarm. Does not seem to rinse - water is still soapy after 3 hrs but when it stops all the water has gone. In my test it started rinsing after 4 hrs but water was cold again. Checked all the filters and they were in a bad state, covered in a white jelly like substance, cleaned and put back. Have also checked that the water pump impeller is not fouled. I don't know what else to do.
Is this likely to be the thermostat? The e nr number is S5453XIGB/56