Charged for an item that was delivered, after almost a year

I cancelled my fibre service in Jan/Feb 2021 and returned the device with everything the receptionist processed everything and I signed that all was in order. Now early November the Company debit my account which is after 9 months or so claiming that there was a missing equipment. I then went to the office Cape town and found the person who received and signed off when i returned the device and explain my reason why I was there charged R225 and then she says she does not understand as everything was returned .She promised to liaise with the departments and arrange for Refund. I have now been following up and I am told the charge will stand as the item was missing. I am not able to be connected with her due to how the system works etc. Can I have my refund as the charge is not valid...