I have a similar problem and don't really see a solution.
Sliding doors are inherently leaky from horizontal driven
water or air, although they are more or less resistant to
dropping rain.

Driven rain sheets along the window, and builds up as a
puddle at the bottom. If wind won't let this pond run off,
it can build up to submerge channels in lower part of the
door. Either the rail can be flooded (which has to have
free clearance for rollers alowing water pass thru), or
you may have weepage holes (maybe with flaps that possibly
aren't functioning) meant to let water from the rail drain,
but actually reversed in wind pressure.

There are various tweaks you can do yourself to reduce
penetration gaps with screwdriver and caulk. Maybe you
can improve drainage to reduce the wind driven ponding
and maybe you can plant a shrub to slow down the wind.

It's very interesting to observe the door when wind/rain
is coming; pretty amazing how a wall of water pushed
horizontally can exploit gaps leading to channels leading
to exit gaps. You may have more patience than a contractor
to diagnose the real problem.