Service costs refund

Arrived home from choir practice to find a letter waiting for me with the details of the annual reckoning for service costs in my apartment.  Every month I pay rent (called 'cold rent') plus service charges (cold rent plus service charges is called 'warm rent').  These service charges or Nebenkosten (literally 'side costs') don't always include heating but mine do.  You pay up every month and then once a year everything is tallied up, divided by either the number of people living in the building, the number of apartments or the square meters occupied, depending on how the costs are allocated, and then they figure out if you have overpaid or underpaid.  I didn't think I would have overpaid as much this year as I had my lodger living with me for three months at the beginning of last year and was fairly sure that would have had an impact, not least because he was very fond of using the heating.  But I'm actually going to get a refund of a bit more than last year.  So there should be just over 360 euro winging its way to my bank account next month.  Fantastic!