It's unfortunate that you had to shell out $$$$ to have someone fix it for you, because for most MB models, it's a relatively inexpensive and simple fix, and can be done in an hour's time.
Even if you had to replace entire power window assemblies, you are only out about $150-$200 max.
In many cases, there is a $2 part that remedies the problem!!!
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car