Self Assessment Repayment - Overdue and impossible to contact anyone

I filled in my tax return online and requested a repayment that was due. I have a sperate reference number for the refund transaction as well as the self-assessment submission. It hasn't happened and I have not been contacted. Your general helpline (who actually answered the phone!) can confirm that my tax return is received and accepted but that a refund has not been processed. I have seen a corresponding change in my tax code for this year. The helpline suggested that I contact the self-assessment team and requested a manual processing of my refund.......... How do I contact the self-assessment team? Whatever options I choose (I have made >20 calls and exhausted all possibilities) on the 0300 200 3310 number I get sent a text with a link back to your website and then disconnected! Your webchat never has any advisers available. You were remarkably efficient last year when I owed tax! How do I get my money back this year?

Hi Alasdair Shinner,
I'm sorry to hear you have not been able to get through to us to claim your refund.
While our webchat service often experiences high volumes of contact, advisors are usually available between 8am and 8pm.
Please go to:
Self Assessment: general enquiries
And click 'ask hmrc online'.
Thank you.