Humble Bundle keeps cancelling my orders

How about contacting their support?

Short answer is they're thieves that's why.

Long answer is their paranoid minds must think you're some kind of evil reseller so they want to screw you. If your local consumer protection laws prohibit refusing a sale without a (really) good reason, you can try to contact support and tell them that. Otherwise, you can just wait for a (long) time without using your account and you may have better luck later. But I suppose your store credits will expire before this happens...

Things they surely don't like to see: non-residential IP, several accounts on the same IP, phone number not matching your country, declared country not matching their (inaccurate) detected country, etc

Have you change location? Do you use a VPN client?

I would write one more ticket and if again no reply then they must think you are a reseller and you are basically screwed. :x
However usually if they think you are then they would just close it, if it's open there might be some luck.

have you tried waiting? I know that's far from similar but a while ago I had a problem where I couldn't finish a purchase with a similar message. However I was getting humble choice, not anything from the store and I was paying with card, not a wallet credit but maybe their system's just temporarily borked and it'll fix itself soon™. Unless you're trying to snipe a deal that's about to end I'd recommend just waiting a day...

Welcome to the club! You've been shadow-banned by humble. Probably you gifted or sold too many of your purchased games there. Or your IP address was fishy, like too much login from different accounts from the same IP. There is no real solution for that. I say fck humble and buy the games on key sites like allkeyshop

i have the same problem, I cancelled yearly classic, wanted one month new plan and I can't do it :/

I had the same issue, couldn't purchase for several months, and once I got tired of waiting I asked their support for help. It took them 2 days to answer the initial ticket, and another 20 or so days (please note this was during the Christmas/New Year season) to thoroughly investigate my case, and eventually lift the ban. I happened to use my own referall link in the past and they clearly were very forgiving in my case XD

Had the same issue few months ago:
https://www.steamgifts.com/go/comment/EGhlfdM

My first guess is that they want to make sure you're real and have a payment method, even if you aren't using it for the current purchase.
I mean, that's what it sounds like to me.

I'm not sure how you have wallet credit without having a payment method, but I guess there's been a few times I've seen to be able to get wallet credit from surveys and stuff.

And yeah, I would just recommend adding a payment method?

Your account has been temporarily suspended from all purchases due to some suspicious actions on it. Detected by their bot or something. Just wait for your ticket to be answered and either get a support to restore your account to normal, or ban you entirely.

They have 2 types of ban.
They can ban from new purchase(s). Still you can access to your old games.
They can disable your account and no more access to your old games, if you have active subscription they are still charging. Since they wont reply any of your tickets, only way to cancel your credit card.

Update: My issue was solved.

Initially, their support hadn't answered to my ticket, so I decided to write them a new one. After that, they replied to the first ticket, since "the first it was mistakenly omitted". They told me that my account was involved into some suspicious activity, lifted my ban and issued a "one time warning". I had also wrote them something like this, which, let's say, could've helped me a bit into "validating my point":

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Hello, since some time passed and I haven't got a response yet, I've looked more on the internet and I have seen that more people had a similar problem. Apparently, I can't buy more bundles through your service, which, by my mistake, it all happened because I made a new account, instead of trying to contact support or recover the old one. I'm admitting my mistake, and I promise you that it will never happen again. My kind request would be for you to forget me, and for me to be again part of this community.

/////////////////////////

So if any of you have a similar problem, I'd say to keep trying reaching to them. Also, if you lose your account, try to recover it instead of being a dumbass like me and making a purchase with a saved payment method from a different account.