Midcity inflated my bill, failed to deduct deposit and are not responding to my queries.

***, Beverly Mathibela informed me that the deposit will be deducted from the total amount owing. I received an sms on 05 Dec 2019, that I owe Midcity R 841.00. Same day, I tried to call Beverly with no luck. I then sent her an email requesting confirmation of banking details and total amount owing. She di dnot respond my email. Friday, 06 Dec - I called her 3 times, with no luck. Monday, I received a statement that I owe R10 136.00, they added sms fee charge, late payment penalty and only R100.00 was deducted as a deposit.