A 'bank' which cannot process a simple debit order instruction?

This is not a bank, it is circus. After having no problems whatsoever with our Discovery Card for more than a decade, when it became Discovery Bank, there has not been one month without an issue. Instead of deducting the total amount owing, as had been the case for years and years, the Bank suddenly started deducting the final balance. After numerous phone calls, they would reverse the erroneously deducted amount, only to do the exact same thing again the next month. This is basic stuff, banking 101. How is it possible that Discovery "Bank" cannot get a simple debit order procedure right?