Cruise control Issue

I can't believe cruise control on your car won't set above a certain speed have you checked your owners manual? (Check here http://repairpal.com/automobile-owners-manuals-online or try this link you may be able to down load a free copy of the owner's manual for your vehicle http://www.autousermanual.com/ ). I hope "Zee" , Roy or Dan see your question they are far more knowledgeable than I am with Mercedes. Perhaps post your question to Mercedes specific forums.