I think that you never need it. Because , it has no belt, it has chain instead.
belt
Need a picture diagram of poly-v belt routing for a 1999 Merced es Benz C280
It has a chain for timing. There is only a poly V belt for A/C, alternator, and the other accessories.
There is an electrical connector located under sear that connects to seat belt buckle, just disconnect it.
Take it to a mercedes garage
how to change timing belt mercedes benz E200 1.8L 2008 model
how to change poly belt on 2003 E320 mb
Mercedes c200 cdi hasn't got timing belt. Has got chain.
it has a timing chain no need to change it
how to change the v belt on c320 mbz?
How much it is going to cost
Don't know looking for instructions.