Beko DW686 Dishwasher Keeps filling with water Error codes E1 and E2

Hi - Beko DW686. Our Dishwasher didn't drain so I took of the lower panel and saw a blocked pipe from the sump. I cleared the block and the dishwasher worked again for 2 or 3 washes.It then got stuck on drain again. I took the lower panel off and it had some water in it causing the float/flood switch to engage. I looked for leaks in the pipe I had unblocked but it seemed alright. I cleared the water in the lower tray and restarted the machine. What seemed to be happening is the machine is draining then filling. It then stops for a minute or two and starts filling again, it keeps doing this until it floods, trips the float switch, and drains again.I ran the diagnostic test and it says it's not getting any water, but it's the opposite; it's getting too much water.So I checked the inlet impeller- which is spinning fine. I then removed and checked the reed switch in front of the inlet impeller and that has continuity when I put a magnet near it. So that seems to be fine. I checked the wires from the reed switch to the main board and there is continuity there as well. I put a multimeter (on continuity) on the reed-switch pads whilst the dishwasher was filling and expected the multimeter tone to go on and off but it remained silent -do you think it's because the impeller spins too fast for the meter to register, or is it evidence that the switch is not working well enough. Could the magnet on the impeller have lost charge? or could the reed switch not be sensitive enough any more?There seems to be another reed switch on the salt dispenser/water purifier unit. It has what I though was a float magnet switch near it so I though that perhaps it was not floating properly, I drained the salt dispenser and removed it and the magnet moves freely when I tip the unit upside down. I also removed the switch from near the magnet (whilst it's still wired) to simulate the magnet part moving but that had no effect. DO you know what this reed switch/magnet are for?I'm stuck now I'm not sure what else could cause the diagnostic to think there is no water.