Beware of double charging for post box rental

I have just been forced to pay double rental for the post box as it was locked by the post office.As I try to be a diligent customer I had already paid the rental in November last year before the renewal notices came out (which never came). <br> Please be aware that the data is not correctly captured by the staff and that you must keep your receipt 'ad infinitum'. I had unfortunately discarded the receipt and was unable to supply proof of payment five months after initially paying the rental.<br> Next year the post office can expect my belated payment only in January/ February, if I even decide to keep the post box that delivers mail so tardily