First off attempt to clear your cache and see if this will remove the patches if this doesn't work like in my case then this solution is for you.
This solution is not for people who hate glitches or ways of getting around patches, instead it is for those people who are having extreme difficulties with obtaining this achievement. All credit for the idea goes to my friend WaviestDouble07.
First you are going to need a xbox memory card or a USB. If you are using a USB then you have to format it for the xbox. This can be done by going to my xbox> system settings> select memory> and then press y on the usb. From here you can either configure the whole thing or a portion of it. Don't worry this can be undone once you have finished. If any of this was unclear see this site: http://support.microsoft.com/kb/981974
Now that u have another storage device you are going to go to My xbox> system settings> memory> the device your gamer profile is on> gamer profile then select your profile and move it to the other storage device.
Once your profile is on the other storage device turn your xbox off, remove your hard drive or what ever everything is saved on and disconnect your xbox from the internet.
Now you are going to start up your xbox and load your gamer tag from the other storage device. None of the patches will be on the game now and you are able to get on the table and easily get this achievement by jumping on the table that is seen in the video below from GrynarGaming. You need to obtain about 6-7 thousand points then leave one zombie and turn on the power. Then return to the top, jump back on the table and continue to play until the thief shows up and kill him.
If there are any problems with this guide or something is not clear just leave a comment and i will answer your question or adjust the guide accordingly and please before voting negative please leave a comment as to why.