How do you fix the center vent on a 1998 C280 MB?

A/C is brand new. Now the center vent does not blow at all. Checked with MB service and they say I need to remove entire dash ($1200 minimum to remove)
and find the broken plastic part which is blocking vent. Can this be the problem? Does it really cost this much just to remove the dash, plus the cost of finding the broken part and replacing that? Is there an easier way to find out why the center vent is not working? All the motors for the vents were replaced last year as well so I've covered just about everything. Hoping to keep this car for at least three more years. Has just over 100,000 miles and been garaged. Live in the desert so I really need the A/C to blow from center vent. Right now the air only comes through the two side vents and the vents going to the windshield. Any advice would be appreciated.

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