I have a washing machine

I have a washing machine that does not seem to wash the clothes, they come out still dirty and when iorning the smell of bo is still present ion the u/arm area. Engineers from the makers service reps stat that the machione has a build up of this dirt and smells and washes and reputs tyhe dirt and smells back on, No kidding i havve this in writing?
What could be wrong, all diagnostics show it to be working normally