Cancellation dirty tricks

I switched to a different carrier 5 days before the end of my billing cycle.  Since I was on autopay I was told that I would get a credit for the remaining days in the cycle.  2 days later I received a letter in the mail saying I have 30 days to return the wireless router or I would be charged $99.  It took me 3 days to get through to someone on the phone after being hung up on twice.  Apparently, the wireless router was ordered the same day I cancelled!!!  When I demanded to know who ordered it and the shipping address the representative said it looks like the order was cancelled the same day it was ordered.  When I asked about my credit they told me I owed 33 cents. After an hour of back and forth I still don't know if we pay a month in advance or during the billing cycle. I was then told that the 33 cents bill was also a mistake and I will receive a credit for the remaining 5 days.  I was given a refund request number so we will see what happens.  After over 10 years of loyal service on auto pay and this is how I am treated.