Why won't my washer turn off when breaker is off?
The diagram below shows a typical electrical breaker box:



Notice how at the top there is a "Main" breaker. Locate this breaker and turn it off. If the washer still runs then it has to be connected to the 240 hot lug screws, shown with the red text in the diagram (a bad thing, call electrician).

If the washer goes off when the main is pulled, but all other breakers do not affect it, then it means the washer is wired to the bus bar, also a bad thing, but not nearly so bad as being connected to the main hots.

If the second case is true, then you may be able to fix it yourself. Turn off the main breaker. Locate the connection to the busbar by using a continuity tester, disconnect it, install a 240V 3-wire breaker, re-connect washer to new 3-wire breaker. If your box is full, install a subpanel.