*****ulent MTN RSA

Been a paying customer of MTN since 1995, I recently upgraded my device after MTN has phoned me NUMEROUS times to upgrade, 3 weeks has gone by, and they bill me R2395.81 but my usual installment is R568. Their excuse: "early contract termination" How it that possible???? I simply upgraded and NO OUTSTANDING FEE WAS SHOWN/GIVEN IN STORE! Now they are refusing to reconnect my phone until I pay the outstanding amount that they have thumb sucked without explanation. They way they are treating their loyal clients is honestly pathetic, I'm really disgusted.