F70 is a flood \ overflow warning, start by cleaning the filter in the base of the dishwasher, and see if this clears the fault.
If it doesnt the most likely fault is the flow control which is around £15 part, and your looking around £35 labour cost.
Since this is a rather straight forward repair its probably worth pursuing however, you will start to find parts are becoming end of life (such as the pump and element) so future failures are likely in the near future.
I would recommend CDR they are very reliable and have had excellent feedback from other customers who have used them, their number is ***** 231607, or if they cant fit you in you could try BDA who are a little further afield on 01506 827482
Good morning do you still require assistance?