Commenity is a HUGE Mistake

I purchased an Inspiron (have purchased 4 pc's in the last 2 years from Dell) we set the payment up to pay the bill in full and 3 days after it was due we received an email saying they could not process the payment because the account did not exist (the bank account) we checked our information and there was NOTHING wrong. So we went to their website and paid the amount in full, then we find out that we have a $20 late payment and they burned my credit for a late payment. Unless this is removed from my account and the $20 waived I will NEVER purchase apower cord from Dell let alone a pc for my business. 

KL