My Contract End this Month,

I'm so angry and frustrated with MTN SA I took out a 3-year contract, and its expiry date is this month. Now consultant tells me that I will be billed for March and April as I should've called 20 days prior. My question is why I should call to cancel the contract which is ending this month because I signed for a three-year contract what kind of nonsense that is.

If you see me taking a contract from MTN again, please kill me.