Unknown transaction on my account since end of May and no explanation

I had a transaction that took place without my consent. I reported as ***** online end of May and i gave time for investigation. I received sms saying they couldn't continue with investigation i needed to send proof of payment (reference ***)

i communicated online and the banker told me i need to repeat the above instruction which i did and again in a weeks time i received same response (reference ***)

I did a chat yesterday (23 June) online and private banker called and put me through to ***** department. I waited for over 45 minutes and i was never answered.

Im really frustrated, I recently changed account number because of debit orders that went through my account which i had to reverse every month. Now a transaction has gone through which i have no knowledge of.

I know because of Lockdown things are a bit slow but for a whole month to pass without me getting response is really unacceptable. Im avoiding going into the bank.