A little over a year ago I spent days and days trying and failing to sign up for a Dropbox Business account.
The "Start free trial" button on the website literally did nothing. If I clicked it enough times, I eventually got a poorly worded error asking me to try again in 24 hours. This happened in multiple browsers. I tried many times over the course of several days with no success. I had coworkers try in case it was something specific to my machine or network. They got the same error.
I opened a support request and asked if they could help me manually open a Dropbox Business account. No, they couldn't. The best advice they were able to give me was to try clearing my browser cache and cookies (I did; it didn't help).
Finally I dug around and managed to find a link directly to a billing form, and was able to sign up by having them start billing me immediately instead of going through a free trial. I signed up for annual billing, naively assuming the per-user annual fee would be pro-rated (like Slack and most other good per-user services do) if our small company hired or lost any employees.
During the course of that year I did end up removing two users from our Dropbox Business account. Since we had already paid for the full year up front, I expected the next annual charge to reflect a pro-rated charge. But nope! The automatic renewal paid no attention to the _actual_ number of users on our account, and Dropbox charged us as if those users still existed.
Turns out the number of licenses you're billed for has to be managed manually. If you have 10 licenses and 10 users and then remove two users, that doesn't affect the license count. You have to remove two licenses manually. And if you pay up front for a year but remove two licenses halfway through the year? Too bad. No pro-rated reduced charge next year. Better be sure to predict your exact staffing numbers a year in advance next time.
Want to add a user halfway through the year when you're already at your license limit? It'll just fail with a cryptic error until you finally realize you need to first go to a different page and manually add a license. And sometimes (like literally as I type this) the Billing page you need to visit to do this is completely broken and just serves up an error that says "Oh hello. Sorry for this little hiccup."
Dropbox's core functionality works well and I have no complaints about it, but everything related to billing is so unintuitive and so frequently broken that I wonder whether they even care about it.
So yeah, I guess it doesn't surprise me that canceling is hard too.