I think its time to take the plunge steve if possible. Money is not good enough in these circumstances. My personal opinion is you need to show the ukba you have a serious relationship. Fiance or spouse visa is the way to go. From what you have quoted from the ukba it seems they think your gf is abusing the tourist visa. I know that is not true. But the ukba think otherwise and it is their decision that counts. All the best mate.