Bosch TKA2801 Filter Coffee Maker

We've had a Bosche Solitaire coffee maker for c.5 yrs, & agree it makes superb coffee, but it has recently developed a fault.

I switch on, then after about 2 minutes it starts hissing like a locomotive letting off steam, and the red lights go out. I switch on again, & the process is repeated. Making 2 cups, I have to switch on about 4 times, & occasionally hot water comes up from the base where the element is & finds its way into the cold water tank. Eventually the coffee is made, but it's a very time-consuming process, & I get the feeling that things are getting worse. If I'm making 4 cups, it takes even longer of course.

I would be grateful for any advice.

Our Bosch TKA2801 coffee maker started to leak after 4 days. The styling is cool but with such poor quality it's not worth buying.