Hey LLZ 44,
Some good advice mentioned from the previous posters. It is correct that it is not unheard of; perhaps at the conclusion of the first interview (when it is likely that you'll be asked if you have any questions) bring it up then.
Of course you will need to be diplomatic and word it carefully but the interviewers may have a different view than the recruiting office.
Give it a go, just stress that you'd LOVE a job as a CX SO, but is it possible to be also considered as DEFO...?
JSB