Please help with mayville post office

I do have a problem and do have a sms i did receive from them. I order my mom a wig because of cancer from wish i been dealling with them for long. This time i ask them to send it to my mom. They ask my mom R110.90 to get the parcel and they suppose to ask R24.00. The post office are mayville in Pretoria i want to know why do they ask so much. All the other parcels we didnt get because of they striking. I need a answer and know what i can do. Because the law say 24.00 and yes the wig have cost me 140.00 rand so why do i have to pay so much