I've used the Burner app for years but it recently locked me out and told me I had violated its terms of service.

 
Hundreds of sugar contacts and threads are gone and unrecoverable. I assume the TOS violations had something to do with the details of my sugar threads, meaning, sexual specifics and $$$.

 
Has this happened to you? And what service do you use for an alternate text #?

 
Rockford

Well, that is shocking. It means that your burner app - actually Burner - monitors texts. You need to use a service that uses end to end encryption, meaning that the company itself can't read your texts.  

What did I use:
Google Voice: complete disaster. I also use a VPN, and each new location led to Google assuming I had been hacked or was a spammer. Kept locking me out. Only really viable if you use a consistent wifi interface or location.

Textfree: Worked fine for many years, but then they introduced a block on VPN connection. Have not used for a few years, so don't know if that is still the case.

Burner phone: My current solution. Use a cheap one, or older discarded phone (in which case factory reset).  Cover story is that it is for emergency use in case of disaster or damage to main phone. A backup. But one can load it up with apps and text away.

I assume you are talking about the app named "Burner: Second Phone Number" that I just found on the iPhone app store.  I have never used it. A brief review of the App store info doesn't seem to include a link to their TOS. Bust based on the app description, I can only guess that the TOS must include some prohibition against using it for illegal purposes, like drug deals, money laundering, terrorist activities and probably prostitution in countries where that is not legal.

 
I have used a Google Voice number for years and have never had this problem. I use the Google Voice number to set up my WhatsApp account as well. So I can give out that 2nd number for direct text or to other WA users.  

 
Sounds like a nightmare for you to deal with. One "Hail Mary" idea comes to mind.  Like any app that requires you to log in with a unique ID, tracks your messages, pics, vids and contact info sent using the app, you may be legally entitled to a full data dump of all data, messages and content associated with your account. If you can contact them perhaps you can request that data dump?  

 
Life is good

 
The Cat