The clutch line is made up of two pieces, the mb specific part # for the metal/rubber one is- 1232951713. this one travels from the master to the driver side of the transmission, the second hard line travels from one side of the tranny to the other.

The second piece can be made out of metric brake line available at most auto stores. In fact, the part is technically NLA from Mercedes, instead they will sell you a piece of SLS suspension line that must be shortened at 20 times the price of a piece of common brake line. The best way to replace this is to take the slave to the auto store, and see which metric line screws in, I am guessing 8mm or so.
If you don't have a bubble flare tool, you can have pretty much any garage flare the line for you once you decide on length.

You need a metric line wrench, rounding the fitting is the #1 most common thing to do without a line wrench, which grabs more sides to prevent this. The existing piece may be salvageable with a line wrench as well.

If you can get the short section of line off (hard to do as they are most often impossible to separate at the rubber section, you can cut off the existing flare, replace the fitting, and reflare it. It will be slightly shorter.

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