Just another question, this political motivation to "slow" immigration is actually happening (like, was it mentioned somewhere official)? I thought it was due to the increase in the number of applications and other internal problems...
I don't think it's really happening like the conspiracy theorists are telling it. INZ officials have to work to a code of conduct, which hasn't been changed. Politicians can alter regulations and quotas, but anything they do is in the public domain, so there's nothing there that we don't know about. As far as I'm aware, the present backlogs are due to two things - an unexpectedly large flood of applications towards the end of last year, and a chaotic reorganization of INZ structure to bring more processing onshore, which was pushed ahead although there had been criticism of aspects of the plans by INZ, who would have to cope with them.
And by the way, unpaid leave with your employer's consent DOESN'T cause any problems for INZ. On unpaid leave, you are still an employee of that company.