Went to get my repeat prescription and my GP informed me they were pulling my SCA. What do I do?

I tried to order my repeat prescription and was sent an email saying:

'We are writing to inform you that, unfortunately, we will not be able to continue prescribing your ADHD medication or arrange further monitoring if your diagnosis was made by a private provider. This decision is based on our experience that private providers often do not offer the same level of follow-up or monitoring as NHS specialists, which can lead to disparities in the quality of care. Additionally, relying on private services can exacerbate health inequalities among patients, as access to consistent follow-up and support may vary significantly. Given these clinical concerns and our current capacity limitations, we as a practice have made the decision to not enter into shared care agreements with private providers. From now on you will need to obtain your ADHD medication directly through the private provider.'

They gave me zero warning. I have three pills left. My job is insanely busy right now and cannot afford this disruption. Can I complain? What do I do next? I'm so fucked off and lost.

Also a big FUCK YOU to the guy that made that panorama documentary. This is the impact it's having. Simply can't wait to fall back into my depression and lose my job! 😭