Cannot change delivery address

I have been trying to get a whole of one your agents for 3 days now. I urgently need to change my delivery address for my package ordered from Rain Unlimited as I am now going to be working from. I have tried changing it on your website and all it keeps doing is telling me to wait. I called your call centre on Friday all afternoon and all of Sunday and was kept on hold the entire time! This is completely unacceptable. I have never had any interactions with your company but it is by far the worst courier service I have dealt with. Why give the option of being able to change a delivery address if the option actually doesn't work??