Double Debits for the month of August

Affinity is my medical health insurance provider. I recently changed my debit order banking details with them which took over three weeks for them to get back to me to make the change I tried to make the change before my July 26th debit order went off and they only contacted me 3 days before the debit was scheduled to go off and because of that the debit order went off on that date 26th July 2019. After updating my debit order dat to the 7th for my next debit which would only be due in September because they had already taken August premium at the end of July they have now put another debit through on my Standard bank account. What kind of unprofessionalism and terrible service is this. They are really annoying because the staff are not taking instruction well and causing me bank charges. I have contacted them a number of time and even complained this morning regarding this matter up till now nobody has called or communicated with me only an automated response on facebook.