Complaint or very bad service

i took a tablet for my child in 2017 and 2019 in January i got a call from Cell c saying in February i must call them to cancel the contract so that they don't debit money from my account from march. i did that in February and was advised that i will not be debited but in march they debited my account twice. i went to the store in Newtown junction and they advised that they cannot assist me because my account is closed. i called the contact centre and was put through to the retention desk where i spoke to a lady for about 15 minutes saying that she is investigating why i was debited, when she came back she said it was debiting for the last time and assured me that it will never happen again. i was happy because i was thinking that they will never debit again. and on the 15th April they debited again and on the 25th April they again debited. i am tired of cell c because everytime when i call they lie to me but still go back and debit my account and when i reverse all this debits i am charged. i cannot take this anymore. please cell c.