So I am curious, and perhaps the OP could clarify...
The suit is still under warranty right? So if the zipper needed replacing, why wasn't this covered by warranty (I understand it wasn't leaking...)
The reason I ask is that SANTI, like DUI moved to the T-zip and they had a huge failure rate. Halcyon here in Canada replaced the zipper, under warranty, without hesitation. Which was awesome...
When I first read the original post, I thought that they replaced a T-zip proactively, under warranty, and at no cost, so I couldn't understand what the complaint was. To charge you for the new zipper, which wasn't leaking, and without your authorization, is BS.
This gives rise to my other question... if the boot repair was under warranty, why did they even have your credit card?
Edit: Hang on... You said:
"Mark never apologized for the mishap. Instead, he said "enjoy your new zipper at no charge" insinuating that I perhaps am the one conning them.
I am currently in the process of disputing the unauthorized zipper replacement charge with my credit card company."
Did they charge you or didn't they? If he said "enjoy at no charge", then presumably what he has done is replace a T-zip which is probably going to fail, with what, a YKK?