Sounds like your ATF is at the wrong level, but the only way to check properly is with the box at normal running temp. after at least a 10 mile run, measure on level ground with the engine running and gearbox in Park.
As said go back to whoever changed your ATF and have them check the level and the source of the leak, but don't go with the attitude that they are idiots , just ask them to reimburse you for your expenses if the fault is their's.

Geo.