Complaint early debit order telkom

I want to lodge a complaint.I got a wifi router with telkom before I went on leave I spoke to Telkom on there chat line on there website why did my debit order go off early.They said it went automatically because it's december they deduct early.I explained to him I'm still working and get paid at month end.Now my bank gets debited with bank charges that negetaviley effects my account..The said they will deduct month end but behold they deducted on the 24 th december 2019 not Monday end and the 15 th January 2020..I made a deposit of R400 plus minus on the 5 th January 2020.Please follow up urgently debit order must go off at month end .Any charges must be paid back.