I work for a non-profit college access program serving low-income students. I wanted to use their add-on for Google Sheets Mail Merge only. Their pricing is very misleading as it says it's only $3.25 per month. So I chose that option, only wanting to use it one time. However, it is really $19.95 per month if you choose to be billed monthly instead of annually. When I contacted customer service via email, they were prompt in canceling my subscription and said my refund had been processed. However, there was never any refund processed. Since then, I have reached out 5+ times through email and their online customer service form, and have had zero help. All they said they do not understand why I want a refund, then continued to not respond to my emails, even after explaining all of the above.
If you need to do Mail Merge with Google Sheets, you DO NOT need to purchase their membership to use it AND there are other businesses out there that can do the exact same thing without charging you and with much better customer service.