lock of box after it has been paid last year

Good day I paid my post box 17 December 2014, there was a mistake and the numbers were switched, my box was locked can't get to my mail, I saw on the proof of payment the mistake, I phone the post office and they will rectify it, they phone me to tell me they did, but it is 3 weeks later and still my mail box not open, so I paid for something I can't use