15 mins to change bank details and still not done

A couple days ago I called telling mobile from my Mum cellphone to change my bank details for my debit order and after 15mins the agent kept on putting me on hold without confirming why this process takes so long and just says my system is slow.Really that slow just to change bank details I then emailed him to confirm if it was done and still no response pathetic service once again from telkom mobile