Can't help with number sorry, but do have a thought that maybe some in the know can comment on.
How about trying a "Freedom of Information" request?
A few of us at my place are in a bit of a "pay mare" Our Admin Office is not entirely helpful and are unable / unwilling to answer our queries. A chap in Glasgow actually recommended writing to Soldier Mag as that would be a quicker way to resolve the situation! In fact one of our contempories from another district did just that and his pay was sorted out pronto!
So is it feasible to submit a Freedom of Information request for this?
As I have said before, it is always difficult to diagnose problems without full facts or both/many sides of the story. But if you say you are owed food money, then I find it hard to believe that this cannot be rectified by your own admin office in some way. I have worked at both ends of the Armpy Pay system, at the unit level and at the mainframe level, whilst there are occasiosn Glasgo may need to sort things out, these are few and far between in my experience. There is very little I could not achieve to fix my guys pay with a Unicom terminal. I assume you were away on Ops or something to not have to pay food charges for 8 months? If so, a Simple "Stop food" should suffice. If for some reason this cant be done, there are other inputs that could be done to get you the money back somehow. If you havent already, I suggest you get your CoC onboard and find how Exactly what has been done so far, and what follow up is happening