Serious delays in issuing new ticket

I have booked an international flight through Flight Centre Blue Route. I needed to change the date of return. Over a month after I have paid in the change of flight fee and gone in to the branch to sort it out and I am still waiting for the new ticket, despite regular assurances (when I contact them!) that it will be resolved!!!! Not the first time I have had terrible service from this branch. I will not be using them again. <br> Tania ******tze