Sorry to hear that your experience using WordPress and CartFlows has been less than ideal. Let me try to address some of what I think you are saying above.
1. Scrolling down or up a page with a button click. Sometimes understanding and explaining technical things to someone else can be a challenge. So for a customer, you try to explain what you want or a question you have, but being new to having a website it can be challenging to ask in a way that someone knows what you are asking. To me, it sounds like you are asking how to create what is called an “anchor link”. If that is what you are asking, that is not CartFlows specific, just a general website question and here is the answer https://www.youtube.com/watch?v=CivIs8O7cUE
2. A font is different on an upsell page. All of our templates are designed by the best designers in the industry. It is very common and even a best practice to use more than 1 font on any design, as a design principle. We stick to 2 – 3 fonts to make our designs visually appealing. Now if you are seeing a font that appears completely random and out of place, this wouldn’t be coming from our design template. Since you are using CartFlows on your website, with your hosting, and with any plugin that you choose to install, it is possible that something installed on your website is causing this in which case we would be more than happy to look at it. Speaking from experience, you can see that when someone installs performance plugins on their site and it breaks all sorts of things.
3. After the last update your page “looks like utter crap”. This also would not be caused by CartFlows. CartFlows is installed on over 70,000 websites and we have never once had anyone report this. To me it sounds like the page template setting was changed. Here is what it should be set to, you want it set to “Template for Page Builders” https://cartflows.com/docs/how-to-use-your-themes-header-footer-in-a-step/
Lastly, I do want to challenge your claim that CartFlows is buggy. It certainly is not buggy and our over 70k users can attest to that. Sure any software is going to have a bug here or there and every time anything is been reported to us, we fix it with priority. We have an entire team of engineers that not only support our customers using CartFlows, but add new features with each release.