Donating a fridge to Charity instead of returning it to owner.

So my little sister left her bar fridge at South Point Residence at her friends room because she didn't get space to reside at Southpoint last year and didn't have transport to move it, she also noticed that the other Residence she got space at, had a fridge for her use. So this year, she managed to get space at Southpoint and currently stays there, it was then she realised that the friend had quit school and left the residence without paying the bill. The friend's belongings were the confiscated along with my sister's fridge. Now we have tried to contact her and her family and they have promised us to pay so the fridge can be released but its been nearly a year now. When I approached the Southpoint Management with the proof of purchase of the fridge, they tell us to go the friend and ask her to pay or we can pay her Res debt in order to release the fridge or else they will donate it to charity. That fridge was purchased with my mother's monthly pension, she could have bought other vital things with the money but a fridge for my sister is also vital but Southpoint chooses to donate it to Charity than return the fridge to the rightful owner.