Upgrade gone wrong

I went in for my upgrade Saturday morning after 4 months of contemplating if I should continue with this network (was with nashua for years who were great). My simcard still did not function Sunday, this is when i went back to the store to help. They could not assist, because the simswops are only done during the week and saturdays. Swopped from micro to nano sim. My old simcard was in a non working condition after I left MTN on Saturday already, so I have no way to call or communicate with anyone or thing. Called the callcentre blue with no resolution and just snotty attitutes. I'm use as a tennisball to bounce around between the shop then the callcentre and visa versa. I want to cancel this upgrade with immediate effect!! Sloppy service.