Fasle information shared during sales calls

Poor service and misleading information especially when they require sales.Why am I supposed to pay R432.13 for a billing error that was not mentioned to me when i took up the product? 6 months later I am suppose to accept their 'error' and just pay when i was sold a specifc instalment for specific services. Plesse be honest with clients and do not provide incorrect information at the selling stage just to close a sale. I was told about a specific instalment and now I am told that i must pay an additional amount due to the incorrect billing on my account. Spoke to a lady by the name Mathapelo, no communication of why my account is in arrears, only after i call i am informed about a billing error, that is so unprofessional. When the is an error you send an email or call a client detailing what the issue is....., you do not send them an sms stating they must pay without a clear indication of what they are paying for.