Process to change address unacceptable

We are trying to get a refill oxygen bottle delivered to my mom, who is in desperate need of it. They have however moved over the weekend, and the process in getting the address changed, for the bottle to be delivered, is painful and ridiculous. We have been given a number to phone, from which someone will then need to send a letter to Vitalaire, for the address to be changed, before a refill can be delivered to the new address. This number just rings, and therefore we are unable to get hold of someone to get the process started to changed the residential address. This process does not make it easy to get someone the urgent assistance they need, and in the meantime, my mom does not have an oxygen bottle. Please also consider the fact that loadshedding has been implemented, which means she does not have a back up. We urgently need a refill oxygen bottle delivered and we are not getting any joy out of the process we are forced to follow.