Downgraded from Basic Extra due to a chargeback, but I can't find a way to resubscribe

I had a Basic Extra subscription paid for by SEPA direct debit. Dropbox now downgraded me to Basic because of an alleged chargeback. However, no chargeback is visible in my bank statement (but also no charge for the last month that was supposedly subject to the chargeback).

 

I got an email offering me to resubscribe to Basic Extra, but the option is not offered when I click on the link, only the regular subscriptions starting at €10 (instead of €2 for Basic Extra). I've been running around in circles for an hour trying to talk to someone, without success.

 

Adding insult to injury, I had around 10 GB space in my Basic account before upgrading to Basic Extra. Now I'm back to 2 GB, and since I use around 9 GB, I expect my account to be suspended any time unless I upgrade to Pro, which given this dearth of customer support I'm not keen to do.

 

It almost looks as if Dropbox was out to hook me with a few months of Basic Extra only to then throw me out on flimsy charges to force me to upgrade to a subscription that is five times as expensive. I hope it's not so and they just had an internal billing problem, but how to get them to correct that?