Customer S… This mailbox is full, you are being transferred to the attendant

I tried to pay for my college classes today.  Tried.  As well as trying earlier in the week.  Accept that the folks responsible are – shockingly – busy.  And thus when I get transferred to their voice mail I also get transferred to the operator at the college because I can’t leave a message in their full mailboxes.  So tomorrow I’m going to drive down to the school, between the hours of 9:30 and 12:00 and pay for classes.

Query: How many phone messages does it take to fill up a voicemail box?  And why do critical-to-business employees have a quota in the first place?
If people want to pay for classes let the appropriate employees have a terabyte of storage space so that you can be making money rather than carefully limiting employee effectiveness.