MTN debit order theft

Don't sign debit orders with mtn. For 2 months they have ****** money from my account by debiting on the 23rd for some reason. This after they FORCED me to approve a debit order with an upgrade after I have been paying via eft for 20 years. The are completely unable to manage debit orders. Promises to correct the date are just lies and they now refuse to cancel the debit order and refund me!