(I have no affiliation, I've just been a satisfied customer for a few years.)
These kind of tactics are familiar to me from previously working in the web hosting industry, where the tricks of "the eye-catching price is actually the temporary one, you have to look in the details for the real price" and "a coupon code makes it look like your service can do more than it can" are very common.
So is the aftermath, with many people who are confused and upset when the "temporary" part runs out but not quite confused and upset enough to cancel the service.
The coupon code thing is a little weird, but I don't see how you can complain about it: it only increases your limits. It's just a way for them to offer two types of plans: one for people who like to scan most mail, and one for people who don't.
I used to be an ECM customer way back when, before they tripled their pricing as you mentioned.
I'd honestly be happy just to see a service in the "use us as your mailing address" market with lower and less byzantine pricing than Earth Class Mail ($20/mo plus $5/mo for searchable PDFs, $1.50/piece to actually scan mail, $20 to deposit a check, $4.95/mo to shred mail, $0.30/mo/piece to store mail, etc.) and without the subtly deceitful tactics of VirtualPostMail (auto-applied promo codes that hide what the actual ongoing service limits are, big listed pricing that actually doubles after 3 months, etc).