Request for refund

I got a Telkom mobile contract. I purchased a wrong airtime bundle. After realizing it I phoned Telkom on 12 March 2019 I phoned Telkom twice and requested that Telkom reverse the transaction back to my account. After a long discussion with a agent I requested to speak to the supervisor. The supervisor was busy with a query and I was promised they will phone back. Never happened.

I tried again on 13 March 2019 and that agent was not willing to help at all. The value of the purchase is still the purchase amount. All that Telkom must do is to reverse the transaction.