Clients parcel damaged, now keeps me liable.

I had a package packed in a small box, weight under 1.1kg. It needed to be couriered to my client in Cape Town. Firtly when I walked in, the one lady behind the couter insisted in knowing what is in the box. I just iggnored her question. As I started to fill the waybill (Refilwe) assisted in getting me a quote as the box didn't fall under the diameters of sendining the parcel with the R185.00 courier option. They said I must pay +- R600.00 to courier it with the box. I asked is there any other safer way so they insisted that I must take out the parcels and put it in an envelope. I told them that its ver very fragile and I would like it to be received by the client in good condition. Refilwe assured me that if the parcel has fragile stickers on they handle it with BIG care. What a waste, my client wedding pictures is ruined things she paid lots of money for lifetime memories ruined by Postnet. .. What am I to do now. This is very unproffesional. I will not pay the clients money back as it was received by postnet in good condition an I trusted them with the parcel.. Never using them again!!! I need aswers ASAP! I'll be taken this further!