Still no progress after weeks of making contact with Travelstart on a booking change

I have made payment for my booking amendment that I requested over 4 weeks ago. I am now flying in the next 72 hours and am still awaiting my updated itinerary from Travelstart. I am currently on hold via your call centre, 48 minutes and counting. I was told yesterday that I would hear back from Travelstart and I am yet to have received an e-mail nor phone call.

I would like to be put in touch with a manager or someone who is able to actually resolve issues within your company as your service is non existent and absolutely shocking. Never again will I book through Travelstart, domestic or international!