Hi there,
I am a Joomla expert and working on it for the last 7 years and have worked on many different websites as well as plugins, themes, extensions, and components. I also have experience with ACymailing component and will be able to upgrade it for you.
Please share the website Admin Details as well as FTP so I can check the things and come up with a proper execution plan. You can review my profile over here so you can get an idea of my skills.
Looking forward to your positive response and a great working relationship.
Thank You..!!!