I was offered an upgrade from Club World to First SYD-LHR, cost was A$2000.
£200 sounds exceptionally low for such an upgrade. It’s usually more than that for a WT+ to Club World paid upgrade even on the shorter flights to the Middle East.
It must either be a typo or the underlying Club fare was already fully flex and therefore the gap between fully flex J and discounted F was relatively low.
Doesn’t change the fact that you should ALWAYS check your BA Miles statement, just as you would a credit card statement, and use the online form to highlight any unexpected discrepancies.