How can we improve WHMCS?

February is a month that causes serious issues for us and for our accountant. We need to edit all invoices and set the due date til the end of the month (28th), or else, it also ruins our custom modules that calculate usage for a period of a month.

Here's how it works currently: https://docs.whmcs.com/Billing_Logic#Billing_Cycles

Due to the shorter length of February this can cause some unique behaviour which does not happen for the other 11 months of a year:
Order DateRenewal DateNumber of DaysJanuary 29March 131 daysJanuary 30March 231 daysJanuary 31March 331 daysFebruary 1March 128 daysFebruary 2March 228 daysFebruary 3March 328 days
I am pretty sure this count be fixed. I've sent a ticket so they could have a look and correct this simple issue, but no dice, they simply told us that this has been working like this for 10 years, and apologized for WHMCS not adapting to our needs.

We've developed a series of plugins that do all the calculations accordingly.

Suggestion for correction:

Order DateRenewal DateNumber of DaysJanuary 29February 28
January 30February 28
January 31February 28
February 1March 1
February 2March 2
February 3March 3

This would be the proper way to address the issue, despite the number of days.

What do you guys think about this?
Our accountant has been yelling at us, as it doesn't make any sense. All our vendors bill us for the full month and, in this case, February, that's 1st to 28th February. If that's January, that's 31th January. If that's 28 or 29th January, that's 28th February, period. Regardless of how many days a month has.

This is our suggestion, and I hope it does make sense for some more people. Simply maths, logic applied. February's month is shorter, but that's how it is.