How can I get my £60 credit due to poor customer care out of Apple?

I was given a £60 good will gesture from a really helpful chap called Laurence who was part of the Apple customer support team I think when my iPhone 6s battery failed, I told him I’d save it and wait for the iPhone 8 to arrive which I’ve done. I’ve emiled him back on our thread where it states the amount owed to me and cannot get a reply at all. I have now tried on two different occasions to email my complaint the only way it seems I can through the website by going through and saying there’s a fault with it and saying the problem is not listed. I wxplain in my emails that I’m looking for someone to help me get my £60 credit and could they pass it on to someone that can move it forward and call me or give me the common decency of a reply but all I get is a generic email saying they will reply within 48 which they never do!! I’m so frustrated as I can’t talk to anyone that will help and on one returns any information from my emails.

Does anyone know a way of getting what you’re owed from Apple?

Can any one help or get a member from Apple care take this on and sort it?

Maybe?

I don’t know where else to post this so I thought the store where you purchase stuff will be a good start.