Not acceptable, as you don't know what seeds they are. Especially if you are growing it out for CBD only. I grew a RQS plant before. Had a good time with it, but that is my only experience with them, have heard other not nice stories about them. They have a rep on the site, his name is James. reach out to him and show him these questions and the diary. maybe he can help fix it.
growdiaries.com/grower/james
To their point: Yes plants are living things, but their genetics dictate how they behave. true photoperiods do not auto flower, period, end of story. So the lights are fucking up or the plants are..
This is now a question of WTF where you sent assuming you have fully troubleshooted your lighting setup and confirmed it is not turning off at any other point.
I would argue back to them these points and how you have no idea what is in the package you where sent as that should not have flowered under 18/6, raise concerns about their QA and how this is abnormal and a bad response to something they should be more concerned of. Tell them how you are growing it for CBD only and you now have no idea and they can not prove what you where sent is CBD only as its clearly not what was stated when you purchased it. I would also try and grow the other seeds if you have not already at some point and see if they also autoflower. Gives it is a mix of THC and CBD, it will be hard to tell if it has equal parts without testing. If it was CBD only easy to test, smoke it and if you/a buddy feels high its not good. lol
They should send you replacements, end of story, its their fuck up. seeds cost them very little so this is not a massive cost to them.
If they choose to sand by their 20% off I would tell them to go fuck themselves. Why go spend more money on products they can't stand behind, that's a loose loose in my eye.
Buy from other breeders who don't fuck it up. and write a review on their public facing pages so others know don't get their CBD seeds as you has an off experience with them.
With all this said:
The only thing that would make this somewhat ok is if the strain has autoflower in its genetics as then it can come out sometimes like it is doing now, But I did not see that when looking at their description or lineage. And the only way I would be demanding things like this is if I purchased directly from RQS, and not a reseller, aka a online seedbank that was not RQS. I would be asking that seed bank for a refund or reshipment and letting RQS know they are fucking up, assuming it got repacked, If it did not get repacked and came in OEM packaging then again its a RQS problem.
Most of the time you are not going to get a desired outcome as cannabis companies are not bound by anything like laws or a ethics board. They can and will just ignore you with no real consequences. Its why this industry is kinda sketchy. Lot of white lies and fabricated data points on things to sell a product very little transparency on how things work. Happened to me before will keep happening to others. Best we can do is inform others about it and be a truthful as possible. If you paid by credit card depending on your terms and agreement with them, they can do a charge back "refund". but its hard with weed seeds.
Good Luck!