If you were within the warranty period and were given the runaround that might be the point at which I might escalate things with my bank, CC and I hardly ever do that, but it sounds like a pretty clear problem with the mod. I might mention that it was within warranty period and the vendor did not provide the needed service. It's kind of unfortunate though, if you bought from a vendor and they referred you to the manufacturer. But decent venders will accept returns of the equipment and then deal with the company themselves, quite often, after all it was THEY who were sold a defective product, and they should help you remedy it.
That's just me, but don't let this turn you off vaping, what you describe is really rare, and hopefully will not happen again with new equipment. I'm sorry that this happened to you....
Anna