oli you can download the service manual for your car. When you have it downloaded look at the index of DTC and there you will find the odes C1140, C1141 and C1025. The manual will give you the section and page number to test/repair each of those codes. You can find a lot of information here in permanent "sticky" upper section of trouble shooting and tech section of the forum. Click this link to go to the service manual download, it is free: service manual
You may have to replace the vacuum brake booster or the ABS module. BE CERTAIN YOU HAVE A VERY GOOD BATTERY! A weak battery on a Crossfire will cause a multitude of problems. Many parts can be found on ebay. They will be used, but I have had good luck with them and they are considerable less expensive than buying new Mercedes parts.
I haven't heard of anyone finding it necessary to replace the brake booster on a Crossfire; Are you certain the fluid used in your brake system has always been the correct fluid? Several people have had to change the ABS controller/module, including myself on a 2005 CLK 500 ( which is very similar to the Crossfire )
Use the search box in the upper right corner of the forum and you may find symptoms that you are experiencing and a solution.