Hi, my name is Paul & I will try to assist you
On the CL model the pivot joint is built into the front lower suspension joint
see this picture - the joint is in the centre of the arm:
From memory a new arm from mercedes is around £200 - £250
The main problem with replacing these is that the screws that hold the front strut to the lower arm joint are very prone to corroding & seizing into the strut & can often be very difficult to remove & may even need drilling out which can result in damage to the strut, even when being very careful! This may lead to a replacement strut being required at over £1000 each.
I would keep spraying the fixing screws with penetrating fluid for a few days before attempting to do this job as it may help free up the screws if seized. Always have the screws replaced when doing this job.
Labour time to replace the arms (if all goes well) is around 2 hours plus a 4 wheel alignment check & adjust following the repair
Let me know if you need anything else
Best regards, Paul
Do you mean the pin in the middle that connects the strut?