Thieving *******s Crying over Cents their System did not take

Just got a "debt Administration" email from discovery claiming we owe them R434.66 for Medical savings that we over utilized and had to pay back due to downgrading from Coastal Saver to KeyCare range. After multiple transfers and long waits on the line, im told that their was an Amount owed to discovery for about R2600 that we had to pay back since we used all our MSA due to premature Son in hospital. we made an arrangement with them and they debited my wife's account accordingly. Discovery is Claiming that we owe 1 months payment saying the Debit order did not go off. THAT WAS in 2017!!!!!! No Phone call to say this Debit order didnt go off, no email to tell us it did not go off. No nothing. My wife pulled Bank statements for January 2017 which they claimed did not go off, and she had the funds available in her account, and i do not see an attempt from Discovery to take the money??? no debt and reversal due to insufficient funds nothing. so now, 2 years 9 months later, they send me this debt administration email saying i owe. Why not contact me January 2017 and say it did not go through?? All you big corporations are a bunch of Thieving *******s Making Tax paying, Law abiding citizen to pay for your ****ed up mistakes... I will pay this Puny amount you Crying over then you better make sure you lose my email address.