How do I change my CSC?

[gyrex]

Hi guys,

I'm hoping someone can help me change my CSC. I keep updating my phone using ODIN and downloading the large ROM files but I'm travelling and internet connections are rather dodgy and have limited download capacity and really need to update using OTA!

The latest update I've applied is DBT-I9505XXUGNF1-20140619102758.zip

Software version: I9505XXUGNF1
CSC: I9505OXAGNF1 (Note: Not DBT so OTA probably won't work)

Is there some way to change my CSC to DBT? OTA says I've got the latest update and there aren't any updates available.

Thanks in advance for any help...