Call Centre unprofessional

At about 09:27 a guy with the name Zane phoned me. He offered me another deal to pay less on my account. they always says calls are recorded for quality purposes etc. But as soon as you say you would rather leave your contract as is, it feels they get irritated and without a warning or goodbye they just put the phone down in your ear. I feel this is really unprofessional. If I had to do that in my workplace I would have gotten a warning. You don't do that! I have been a client of Vodacom for 19 years. This is not the first time it happened and if it happens again i will definitely cancel my contract and go to another service provider. this is unacceptable.