Hopefully someone from Bytemark can answer this.
Today I received an email detailing your latest T&Cs and one thing I noticed I feel needs clarification.
“One example of this would be customers who are still choosing to operate their code or application on PHP 5.6, when the current in support versions of PHP are above 7.1. While we provide the frameworks to customers in order to provide a wide range of compatibility, it is unrealistic for us to support issues relating to those frameworks.”
Given that your own Symbiosis installer falls short on the PHP version, installing 7.0 not 7.1, will you honour support in this case. Debian are continuing support on stretch for that version of PHP so I assume you too should not have an issue there.