simcard

I purchased a contract phone with MTN about a week ago and only to find that the sim card was not the correct size (small) and does fit in the phone. I contacted the number *** to report the problem and also to ask them to replace the sim with the correct one. I was told that they can't assist and I have to buy a new sim. this was unacceptable as the package comes with a free sim and I was not liable for the wrong sim cards. i went to an MTN outlet where they refused to assist without a reference. i then called MTN once again and spoke to different consultants and none of them was able to help they all told me that i should buy myself a sim card. question is why should i buy myself a sim when i amsupposed to receive one for free with the package?