Cook Portable Sales Late fees charged and called a liar by "customer service manager" Internet

I received a late notice in the mail that my bill had been received "late" for several consecutive months and called Cook Sales to inquire about it.  I spoke to Scott who informed me that it normally takes up to 14 business days for mail to be delivered to them.  I asked how often they check their PO box because no other bills sent out take that long clear.  He informed me that the payment goes to a bank.  I asked how long the bank holds the check before cashing it and if this is done so that they can charge a late fee.  He told me that they do not hold checks but the last person he was on the phone with was just asking the same questions. Since no other payments that are mailed out seem to have this problem being received in the mail I asked if I could pay online so I could know when the payment was being posted and was told I could not.  I asked if I could pay over the phone and was told I could but that would be an additional charge. 

I received another late notice in the mail and called Cook Sales about it and spoke to John Nice "customer service" manager.  Although I mailed my bill out in plenty of time even according to their mail time frame I was told I had another late fee on the account.  The payment paid the late fee first so that month's payment was not considered paid in full so they charged me another late fee.  I asked again why if I mail my check out in plenty of time did it always seem to arrive to their company "late" and why do they not send out notices that they are imposing late fees. Is this so that even if you mail your payment out 15 days before it is due you will still be charged a late fee?  At this point I had received 2 late notices in the past couple of months but had received late fees every month.  John told me that he did not believe I was sending the payments out on time.  I asked him if he was calling me a liar and he stated that yes he was. I told him that I was not a liar and  I asked him if I could speak to someone else and he said no.  He said that I could write a letter to someone named Joe who based on the content of my letter may or may not call me back.

This company gives you no way of keeping track of payments except when they are cashed at the bank.  I guess if you want to know if you are being charged late fees you have to track you bank statement to see when they clear the bank to know if you need to add money to your next payment for late fees so you don't get charged another late fee.  And to be on the same side mail your payments out a month in advance. 

According to John this is a "huge company that has been in business for 27 years".  I find it amazing that I am not the only one who has questioned their "late fees" and then am called a liar.