Were Upgrades by IWC Service Optional?

Greetings all. I'm not certain I have posted this inquiry in the correct
forum, but here are my related questions.

For older watches sent to IWC for service, were upgrades (new
bracelets/cases/dials) suggested/optional? Or did IWC insist on upgrading
hardware? If a consumer refused IWC's recommendation to (for example)
replace an old dial for the newer design, would IWC still carry out the
consumer's request to service the watch? Would IWC refuse to service the
watch? Or perhaps offer to service the watch but not offer a warranty on the
service if a consumer refused to replace the dial?

To be completely transparent, I am thinking specifically of the Titan
chronograph (as I frequently do!), and Porsche Design models in general.
Drawing from Titan chronograph examples, I have seen early watch cases
upgraded with later bracelets and dials. I have seen later watch cases and
bracelets with older movements and dials. I personally had a Porsche Design
Ocean 2000 (first version) that the IWC Service Center advised (in 1992)
needed a new dial and case/bracelet with the service. I don't recall that it
was optional, and was under the impression that if I didn't agree to replace
the case/bracelet/dial that the watch would be returned to me.

I'm trying to piece together why I would see the Titan chronograph examples I
mentioned above. Could a consumer have directed IWC to keep the old dial but
replace the case and bracelet? Or keep the case but replace the bracelet and
the dial?

Thanks in advance for any feedback drawn from knowledge or personal
experience.

So from what I've heard, when the original geometry bracelets of the 3500's
and 3700's started getting loose IWC they made the 2nd version and that too
failed so they made the 3rd (and 4th). If you sent in your watch to IWC for
that fault they offered you the replacement they had at the time. Realize
that the owners who sent theirs in for service because the bracelet wasn't
holding up were offered the new one as the remedy. Putting yourself in the
mind of said owner in the 90's or even early 2000's, they weren't thinking
about the watch's originality or future value based on original or replacement
bracelet (and case to match). If you sent it in for another service they were
supposed to ask if you wanted the "update", you were free to decline. Also,
if someone was pondering trading away the piece after service, it'd be hard to
turn down a 100% new case and bracelet, it would likely give you more trading
value for what you were looking to get next.

This does lend itself to the rarity of the originals in good shape, i.e. the
unworn or lightly worn. And here we are, chasing the vault queens.

When I brought my 3701 (Black on Black) to Superior Watch Service to be looked
at, and just to be clear, I have a VERY nice example that didn't have much
wrist-time. He told me that I should be careful because parts are completely
unavailable for the 3701's bracelet, and that was in 2012. Imagine someone
selling a NOS 3701 Black bracelet on an auction site today, that Delrin
bracelet would probably fetch a very large sum, I know I'd bid.

I think the take-away should be that "most" owners sending it in to service
back then (now 20-30 years ago) weren't thinking of the effect on originality
of the piece that upgrading such things would do - and did it because they got
it refreshed to a new state.