Struggling to get my refund from Edgars ... requests falling on deaf ears

I recently end of June paid up my Edgars account as per the outstanding balance on the statement - which I realised afterwards I should perhaps have attempted to get hold of them. Nevertheless, they contacted me back within a few days to advise I overpaid - and its been endless issues since then trying to secure my refund and the request to close the account and mark as paid up falls on deaf ears. I have had this account for well over a decade or even two decades, and I am not entirely shocked at the lack of customer centricity but it does however leave a sour taste, I did the right thing in paying my perceived outstanding balance. Not sure why they wont do the right thing and refund me and close the account. Truly disappointing to end the relationship on such a note.