In the short term, just to get their attention, send them a warning letter stating that they have damaged common property by putting a bolt on the laundry door. Then find out what the problem really is … perhaps they are worried about people scratching their car as they pass with baskets of laundry.
Your solutions may be to put a fence around the car space allow a clearly defined walkway to the laundry or even finding this person another space for their car and then creating a permanent right-of-way through the now-vacant space.
Either way, it would be worth checking your strata plan to see who owns the space (is it private or common property) and whether or not the right to access the laundry has been established in the plan. Establish communication but make it clear you are prepared to compromise, if they are, but you have options if they refuse to discuss it.