Postbox Locked

Good day,<br> <br> I have rented post box, number 12436 at the Tramsheds branch.<br> <br> For the past 3 weeks, my box has been locked for no apparent reason and I cannot access any letters received.<br> <br> On 6 June 2015, I enquires from the branch that several boxes were closed by post box management from head office.<br> <br> I asked if the branch manager can open my box as I do not owe the Post Office and I was told in no certain terms will they open the box for me and I must contact their head office.<br> <br> I feel cheated by the post office and it's attitude in that they can unilaterally close the box, in a way breach the contract entered into with them.<br> <br> I need full explanation on why the box is closed.<br> <br> Regards,<br> <br> Masilu Kgofelo