Wrong SIM card sent

I have upgraded via Mobilesplus and received the phone on Thursday (08/10). They sent me a micro SIM but the new phone uses a nano SIM. I got a new nano SIM but can't seem to do a SIM swop. I went into the MTN store but they were not of much help. I am very disappointed in your service Mobilesplus because I have spent a really long time on the phone trying to get my new phone connected. It has cost me a lot of money because my nearest MTN store is 95 km away. Also I may need to pay R136 to MTN to give me this service all because of you sending me the wrong SIM card. This is unacceptable and I do not want to do business with you. After the third time calling you I was told to wait on the line and you cut me off. Who is suppose to carry all the costs not even to talk about the inconvenience you put me through. Unacceptable!