If you sold on this account, your money will be on hold for 30 days as you are considered a 'new' seller 

How was the item delivered?  

Did you post it?  did you upload tracking? 

Hand deliver it or the buyer pick it up, and if so did you scan the QR code as required?

You say you will never sell again, yet you have 2 active listings 

eBay Help is at the top of every page

BUT if it is simply your funds are on hold as they should be, and as you agreed to when listing, then there is no point contacting cs. Especially if you cannot prove delivery plus the buyer has not left you feedback