Manitou Swinger 4 rear shock query

Hi All
I have just bought a second hand Swinger 4. I know, don't buy second hand shocks and expect them not to need servicing but I lapsed and thought I would take a chance that of course didn't pay off. So the damping doesn't work, a problem that can only be sorted out with a trip to the shock docs. That I can live with.
The problem I really have is that it was sold to me as a 200mm eye to eye length shock. After fitting it to see if it worked, the bike looked a little low. Took it off to find it was a 184 mm unit. Now the fella who sold it me has said I used magic to make it 16 mm smaller and it was 200 mm when he sold it. It holds air well so is at full extension? That reall y is my question. Can this shock extend anymore to reach 200 mm or is the seller a fantascist? These units have a nice serial number on the top.
Can I get a definitive answer from Manitou on what size it was manufactured to. Sending it off to TF or Mojo is an expense I don't want for a shock that is 16 mm to short for my bike.
What are your thoughts o knowledgeable ones!

He probably mesured wrong. You should be measuring from the centre of each hole. Rear shocks are set in their length there is no way to extend or shorten them. Sounds like the guy just doesn't want to part with his money. Worst case sell it and get a fox haha

Re:

Hi thanks for the reply.
Unfortunately it was me that was the unlucky recipient of the shock and I am trying to get my money back. Turning into a bit of an eBay shocker as he now is saying I didn't pay for it. Don't do cash deals with eBay strangers. It can all go really wrong!!

What!? Did you pay through PayPal? Why the hell would he send somthing white no payment? Seems like a dodgy seller