Hi Marcof,
Sorry to hear about your experience.
Looking at the information shared above, it seems that you have been experiencing this problem with only a specific pdf conversion? Have you checked with a different file?
Try the conversion using desktop application Adobe Reader DC Adobe Acrobat Reader DC Install for all versions and see if that makes a difference?
The quality of converted document depends on the quality of the PDF file you start with. For detailed information on this, you can read the related article here- Text is garbled in a converted file | Adobe Export PDF
Also, you can cancel the subscription from your Adobe account itself, for that you can refer Cancel your membership or subscription | Adobe Acrobat, Document Cloud PDF services and follow the instruction given there.
Regards,
Akanchha