Requested 500mb recurring bundle was not allocated

At the beginning of may I requested you change my 250mb recurring bundle to 500mb recurring. the agent assured me it was done<br> <br> I checked on the 1/6/15 and saw the old bundle of 250mb had been allocated,when I checked my proposed invoice i saw you are charging me for a 500mb bundle I contacted the call centre immediately and they said they will resolve this, nothing has happened and it has now been two weeks<br> <br> Please allocate this immediately and refund me for any out of bundle data used because you did not do as requested