Blackberry services removed

After 4 years of not owning a blackberry, the company is still being charged for blackberry services. After calling to get this reversed, the only information provided by the business and complaints department is that a company letterhead needs to be submitted asking for the services to be removed. What about the credit that needs to be passed. Furthermore, this incorrect charge is as a result of the sales person upgrading the contract! When the contract was upgraded to a Samsung handset, the blackberry services should have been removed. Now the customer must be inconvenienced to submit further documentation. MTN should investigate on their system what cellphone was upgraded and when and reverse their charges as this is due to an error on their side. Why should the client be further inconvenienced. The attitude of the telephone consultants is terrible as they can only advise on procedure and can not deal with a frustrated customer.