Siemens dishwasher help please SN66T091GB

Hi
I’m after some advice please on my Siemens dishwasher. 7 months ago we moved house and inherited the integrated dishwasher. There was obviously an issue with it that we weren’t told about and it has just got worse. I took out a Domestic and general policy on it as well when we moved in. After a couple of weeks of use, it started giving the E24 error code. I looked this up in the manual and it said it was a blocked filter, so I cleaned the filter. It then seemed to work ok. However the code kept reappearing until it got to the stage that no program would work and I kept getting the code. In December I contacted d&g and they sent out a technician. He changed the pump, although said at the time he didn’t think it was that, but didn’t know what was wrong and to monitor it. It only went a few days before happening again. I called them out again in January and a different engineer took a look and just said to monitor it. I’ve just had a third engineer out who took it all apart, checked everything he could, even the drainage and our drains and still couldn’t find the issue and again said to monitor it. In the week since he’s been it’s happened 7 times out of 10! I want to try and fix it, can it be fixed? Is there anything else I can do? I don’t really need to hassle at the moment of getting a new one.
thanks
Heidi