What's the difference between Final bill and closing bill?

I like many others switched to Sky, rang eircom, submitted cancellation letter by registered post. Sky switched me before my months notice was up, so i have no problem paying eircom for that month. I got my normal bill in the post, a day or 2 later got a final bill in the post. I rang 1901 to figure out which one i was supposed to pay as it really wasn't very clear on the final bill. I got thru to what had to be one of the most unhelpful sourest "customer service" reps on the phone. He obviously could see that i was closing the account and did his utmost to be hostile as possible. Anyways i asked very directly and clearly would i be getting any more bills from Eircom and he said no i would not. Lo and behold roughly a week later another bill lands on my doorstep- this time a closing bill. Again rang up and told that this was the last bill and don't know why i would have been told otherwise. Reading thru another forum here regarding a query as to why vat was been charged on bill that is in lieu of notice/cancellation charge, i dragged my heels to pay it, just to get a threatening letter in the post today.
All i want to know is why can't eircom get it's act together, train their staff to tell people to expect another bill or why not just send one absolutely final bill altogether. In this day and age is that too much to ask?