How do I replace bosch dishwasher aquastop

I’m in the UK. How do I replace the aquastop. I am having to manually drain the base so the the float doesnt keep tripping the microswitch every 3-4 days. I have noticed that the chamber leaks into the moulded base from the aquastop unit and that the float/switch is sensitive to any water in the base. Once i have emptied the water the washer works fine on all programmes (Intensive 70c, auto 55-65c, eco 50c, glasses 40c, quick 35 and pre-rinse). The aquastop is located at the bottom of the left side tank that fills with water that is to be used for the next instruction (like rinse or wash).

Unfortunately there is no on-line access to any diagrams or other information for not American models.

Gene.

quite possibly there is a problem with fill valve which allows execessive amounts of water under pressure in