I have an older s3 that is off-network, How can I get the kit kat update on my s3?

Question

I have a "retired" Galaxy S3 that I am keeping as a spare-  The Kit Kat update supposedly has been available since 6/20, but I cannot get the software on my off-network phone to update-  even though is is connected by wi-fi.  I spent about a half hour chatting on-line with tech support Monday, 6/23, who assured me that is would update over wi-fe-  although I have NOT been able to do so yet.   I went into the Verizon store yesterday, and the woman I spoke to there told me all I had to do was swap SIM cards with my active phone, then casually mentioned that if I did that, it would void the warranty on my new phone by taking it off-network.  Great, just what I would want to do...
I am seriously considering re-activating it for a couple hours, just to get it updated, then deactivating it again.  It would seem there should be an easier way.

Answer 1

Thank you for the prompt reply, but still unsatisfying.  I spent a couple hundred dollars for this phone less than 2 years ago (not to mention the $600 for the S5 off-contract a couple months ago) and you are telling me that I have to void the warranty or open a new data-service line to get the proper support for my Verizon-branded device?  At this point the S3 is off warranty and primarily used on wi-fi-  I could just as well root it and run custom ROMs I suppose-  nothing to lose at this point, since the company that sold it to me won't even help to keep it up-to-date.  I don't mean to sound like a whiner, but this is not what most would consider good customer support.