Tax refund on Self Assessment

Hello, I am a non-resident, French, I live abroad. I had UK tax taken of GBP4,254.75 from an amount of 12,010.40 coming from a restricted incentive award of GBP278.32 and restricted equity award of GBP11,732.08. I applied for a refund, which in my calculation should be GBP4,254.75, after deducting the personal allowance of GBP12,570, but I have received a refund of GBP1852.75 only. I would welcome help. Many thanks to this forum, it is very handy to be able to raise questions, I really appreciate it.

Hi,
Unfortunately, it is not possible to review personal matters in this forum.  
For individualised assistance please contact our self assessment helpline or contact our webchat Self Assessment: general enquiries
Thank you.

But that doesn't work, nor the webchat, nor the self assessment helpline. I have spent an incredible amount of time trying to get someone there, but I have a chatbot which only gives me unappropriate answers. So I don't know how I can get individualised assistance from here really. I just want to cry.

Hello, I was finally able during a European trip to contact HMRC and the correction has been duly made, it was initially my fault, having forgotten to tick the right to Personal Allowance box #16, despite notifyng of my nationality. Thank you again to all services.