Unable to change address

I received an sms to inform me that a parcel is on the way for me. With the sms there is a reference number and a telephone number. Unfortunately I needed to change the address of the delivery but when I called the number of Dawn Wing (given in the mentioned sms), the lady said that because it's an East London parcel, the East London branch can deal with it. She was helpful enough to put me through to the East London branch but there I get stuck. The phone is answered and I'm transfered but then nobody picks up the phone again. I tried a second time and after being transfered, the phone is picked up but nobody speaks. I made a third attempt but then couldn't get through. I then sent an email (yesterday 17 September 2018) and asked to have the change of address confirmed. I haven't received a reply yet, so I sent another email this morning. Is there anyone at Dawn Wing that can assist with this matter so that my parcel ends up with me and not someone else due to the address needing to be changed?