That is peak shittiness. Thank goodness your Mum has you to advocate, and I shudder to think of how many others don't and were shafted or continue to be shafted.

Their competition for PDF Reader; Foxit, jacked their prices up considerably this last year too. It used to be an affordable alternative. They too got greedy (I assume since Adobe was getting away with it!) and have lost a considerable amount of customers in both the consumer end-users and the business side.

PDF becomes increasingly more used and 'standard' with the fracturing of ability to edit them or do 'advanced' tasks like merging multiple PDFs.

There are some alternatives which are free but also either Freemium or just plain questionable in their usage. I don't want to trust some random company and I don't want to be nickel and dimed for basic features like merge.

I spent a long time testing and trying tools. Sadly nothing as comprehensive as what Acrobat offers, but not an option at their pricing. Same with Foxit. I use PDFsam for some basic merge stuff. An interesting project is also Stirling PDF. but pdfsam is like Freemium and Stirling I'm pretty requires docker and it's also not in all languages.