I too have a C220 (96 - 278k miles). Haven't had this problem. If u would have said it turns but doesn't start, then it most likely is the ant-theft engine disabler. Simply lock and unlock vehicle with remote key or key on door.

It could be that you've drained the battery after soooo many attempts that it won't turn anymore. Have u tried jumping? If it turns when u jump, try the above suggestion.

It happens to me once in a while.