
Sounds a bit strange
I installed/ran one of the first cable billing systems at Jones Cable / Bell Cablemedia, and even then (over 10 years ago), if a customer cancelled services, a credit was automatically raised (as line & package rental was a month in advance, if you cancelled after the bill was generated, but had paid your bill, you were owed money for the part month you had not received services).
I have changed services (added Sky Movies for Christmas, and then taken them off a month later), and a credit was always applied to the bill on reduction of services.
Seems that billing systems have got worse in the last decade

or
They are talking bolleaux