I informed Telkom on the change of my bank account 3 months back but they still send the debit mandate to the closed account now I'm charged R206 everytime the debit order bounces in just March I paid R353 and I'm still required to pay R350 just in March

I informed Telkom on the change of my bank account 3 months back but they still send the debit mandate to the closed account now I'm charged R206 everytime the debit order bounces in just March I paid R353 and I'm still required to pay R350 just in March 2024 but my monthly subscription should be R149pm.I sent the complaint the consultant 2 days back still haven't gotten a feedback regarding this issue.