As of 25th September 2016 I will no longer subscribe to Kindle Unlimited, but the four remaining books I have borrowed I will read and review by this date. 

In future any review requests that were relying on Kindle Unlimited will have to be accompanied by a review copy of the book preferably in mobi format.

My reasons for cancelling the subscription is that the yearly fee I pay for this service could be put to much better use.