I can guess why they will ask for the money 1 month before handover because they can then threaten to not hand over the unit if we withhold the amount. Also, every time someone re-sells their unit before handover the developer makes 2%, so they win each time. Like you, I might sell, but even if I pay the extra £3000 do you think its worth it because I only paid £51000 (as resale) for a 12th floor flat? I have seen studios on lower floors advertised for around £56000 in the last few days!
My unit is studio on floor 12. What about yours? Are you based in Dubai?