Exorbitant service fees

Hi trust that you're well after being quiet for sometime. I'm going to take you back to the review i sent last year about the shabby treatment and service is received from Vumatel mweb. Maybe I should give you a brief background about it. I had connected to Vumatel for internet connection (fibre)which the first month was for a trail and will start to pay in the second month but instead they decided to debit my account on the trial month. When I took it up with them, they failed to respond to my email. I then reversed the debited amount. Then they retaliated by cutting off my internet connection. Around October or so they handed my debt to attorneys (Lexmed debt management).The debt started at R504.55, and responded by arranging that I'm prepared to settle the debt in three installments and if it's ok they should revert to me so that we can confirm amounts to be debited. They didn't respond to my suggestion. Subsequently I received an inflated amount of R698.00 and today (11 March 26) i received a call that the amount has gone up to R724.54 and must be paid in cash. I asked him(Lufuno Bebeda)to send an email to reflect the amount demanded and said the email will cost me R75.00. Is this fair and legally?