As somebody who has followed this thread, and two similar threads, I can comfortably say, based on numerous posts, that spending patterns, amounts charged to card, timely payments, or the like, have absolutely nothing to do with whatever is offered to you as a so-called retention bonus. It appears to be strictly haphazard and based on nothing more than whoever answers the Diners phone and what their mood is. Indeed, as noted in this thread and others, numerous posters have reported being offered nothing during one call, then calling back and being offered a generous bonus.
My personal experience: I called Diners customer service. I was told no retention bonus. I asked to speak to the retention department. After a few moments, the Diners customer service rep told me that she had spoken to the retention department, that they had reviewed my account, that there would be no retention bonus, and they would not take my call.
The next day I called the retention department directly, not mentioning what happened in the prior phone call. The rep looked at my account and asked if I would prefer 20,000 points or a waiver of the fee. I took the points.
My advice; instead of wasting time trying to figure it out, just call back.