Hotpoint D/W odd fault?

Model FDFF 1110.
Customer complaint, not releasing dispenser and when set to 60 minute wash timer skips to 30 minutes after a few minutes. No error codes displayed.

Set machine to the Daily A 60 wash setting, it drained, filled and then washed for about five minutes. It then drained, refilled and started to wash again but at this point the display skipped from 55 to 30 minutes. It then washed for a couple of minutes before draining and refilling once more. This time it continued to wash normally with heater operating until end of cycle. Detergent drawer did not open.
Customer only uses this wash because she says other programmes are too long but says that it works normally on all other washes she has tried and releases the detergent????????

I have suggested that she just uses the Auto/Normal wash which is 1.50 hours but I am stumped as to what may be causing this. ❓

Other than a control module fault I can’t think of anything else.