Wear and tear sim in 4 months, impossible!

I purchased a new data contract in December, yesterday my sim card did not work anymore, went in today to MTN New Market mall and the simcard needs replacing, the simcard is damaged and not working anymore, I have to pay for a new simcard now, where they installed it. How can a simcard only last 4 months and now I am liable to replace it? This is not normal, MTN should look after their clients and have better policies and procedures in place so they can look after their clients better. I want a refund.