Lack of clear processes for refunds

I have had a cellphone contract with Vodacom which was suppose to expire in May 2019, but in November 2018 I settled the account following their cancellation process; to my surprise that they deducted again in December and various agents admitted that it was their mistake for not closing off the account and money was eventually refunded back to my account in February and account closed off. Vodacom deducted AGAIN in the month of March and each time I call them I get a run around and eventually told to wait 7 - 14 working days, each time I call after that period I am then told to the process was not done or it was closed in error and must be logged again so I need to wait 7 - 14 working days. today was even worse where I was transferred from pillar to post, one department to the other no one wanted to take ownership of the query till I was told that I must again wait 7 - 14 working days