Poor / None existent service

I currently have a parcel that was to be delivered this week. On Monday I received an email saying my parcel is being returned to the sender and that I must contact the courier company. When I contacted Buffalo Logistics on Monday they told me they don't know why the parcel is being sent back to them by the service provider that was supposed to send the parcel to me, it just says they couldn't proceed. Now I'm being told to wait for the parcel to arrive at their warehouse which might be on Friday, then only then can I make arrangements to collect. I urgently need the parcel and I'm told I cannot make arrangements with the company they failed to deliver my parcel. I urgently need my parcel, no one is willing to make sure I get it as it is not my fault that they appointed a useless company for deliveries. The consultant I spoke to today was not even apologetic, I must just wait. I expected a better service and I want by parcel to be with me by Friday, if not, they can return it to Shein as I will not have the need for it.