POOR SERVICE AND NO CUSTOMER SERVICE

My wife recently canceled her contract with 30 days notice before the next payment date. MTN billed my wife. When we tried to find out why, they advise the contract was not canceled due to an error on their. The cancelation for not done correctly and they now asking us to pay and also go back to the store to cancel again. They think they have a right to inconvenience the customer for a mistake on their side. Is that an acceptable level of service. Their call center's are even worst, takes 20mins to answer and then get passed onto different departments who can't help and you have wasted 45mins of your time and get nowhere. They advertise how great they are with tech but can't get their centre's and system right to service customers and then will get a call in 3 months from them to take out a contract. Like really, after this kind of service, I must take a contract with them.