Electric Bicycle batteries

Does anyone have first hand experience dealing with a rebuilder of Lithium bicycle batteries ?

Local battery stores won't touch them.
Bicycle dealers won't talk about a brand they don't sell.
The manufacturer apparently has gone out of business.

It is a 36 V pack from a ProdecoTech Mariner8
and has "soft" LiFePO cells.

The first "mail order" rebuilder I ran across looked REALLY good......but was all hype and fluff.
The customer reviews included suggestions that they be tortured and shot.
Now I am skiddish.