Cannot unlock cell c phone

My mother bought a phone that was locked to the cell c sim card. Its has been months trying to get the call center guys to unlock the phone. Worst experience ever. These guys dont know what they are doing. Didn't they get training? Is unlocking a phone that difficult? Even when we paid the R150 to unlock the phone? To top it up, the phone has passed 12 months since it was bought now and its still difficult to get proper assistance, or even direction on how to unlock the phone. Does cell c need customers sp bad that phones cannot be unlocked to use sim cards from other service providers?