Unhappy customer

I am not happy with Pick n Pay Hypermarket as I bought a Hisense fridge in 2017 and now it’s giving me problems. They are refunding me, however they first need the old fridge in the store before they can deliver the néw fridge which is more money I need to give out. They are expecting me to pay up front the entire amount of a new fridge before they can refund me. I don’t have that amount of cash. Why can’t they just do a straight swop. I can’t be left without a fridge as my food will go off.