Very disappointing service

I made a purchase online and received an invalid item. I then called in 3 times to request that they come swap the item with the correct one, or alternatively collect and process my full refund including the delivery fee. I called in 3 times and have sent numerous emails but not getting any assistance. This is the second week now. I understand that due to the lockdown, processes are taking longer, but i am not getting any feedback at all. I always have to be the one calling in and always get told that this will be referred to the relevant department. What an inconvenience.