I think your tax office may be getting a little confused and might be under the impression that your salary includes elements which inhibit your claim under the FRE rules. As it does for Police Observers [Serving Officers]. You might need to spell it out to them that you are not paid under Police Pay rates.
I had absolutely no difficulty in obtaining the dosh whatsoever but I did have to carefully explain a few items since the person I spoke to on the telephone admitted that he was not familiar with the circumstance. But he got advice whilst I waited and it all went ok with the cash being set against my tax and it was seen the following month.
Best Wishes
AA