These are Mercedes 722.6 boxes and they are notorious for the nasty plastic seals on the conector to the Gearbox ECU failing.

One of the symptoms (apart form an obvious leak) is transmission fluid leaching up through the loom and filling either or both the the foot well and the Transmission ECU with Transmission Fluid.

This leak will be from the connector at the front of the grearbox on the drivers side.

If it is this, and you are even remotely mechanically competent, it is an easy DIY job and the total proper Chrysler (Mercedes) parts should cost about £10.

Hope this is all it is.