Incorrectly fined for Self-Assessment, paid to be safe, appealed and won. How do I get it back?

I was incorrectly fined for self-assessment for £100. I appealed and was successful but was about to go on holiday so paid the fine to be sure I didn't get an increased fine. Now I have it confirmed that my appeal was successful, I can't find how I can get my £100 back?

Hi,
For a more detailed answer to this question, you would need to contact our Self Assessment team below:
Self Assessment: general enquiries  
Thank you

Hi apologies, there is no link to be able to contact the team. Can you provide an email address?