I have had the worst experience with vumatel, firstly they charge me from the 25 up to the 1st prorata but they do not deduct prorata amount from the balance when i pay on the 13th till the 1st i do not get the discount

I have had the worst experience with vumatel, firstly they charge me from the 25 up to the 1st prorata but they do not deduct prorata amount from the balance when i pay on the 13th till the 1st i do not get the discount. And it has happened twice already. I have now moved homes and vumatel sent me a email and sms stating my line is no longer active.. all good thanks but today i find out that they have provided me with misleading information that is inaccurate and is causing me substantial financial loss. Can a manager please contact me urgently.