QUOTE (BigCityGirl @ Nov 26 2006, 12:21 pm)

My landord who lives above me has decided to increase my rent
Nebenkosten are not your rent but rather the costs of services that you use, such as heating and hot water (which as Carm says, have increased substantially over the last couple of years), sewage, care of the garden, etc.: depending on how big your flat is, 100€ - 125€ sounds reasonable. You don't
have to increase the amount you pay monthy, it's effectively a suggestion based on your consumption last year and your landlord's calculation of how much the costs for those services have increased. However, as Carm says, if you decided not to increase your monthly payment, you could get hit with a big bill to pay next year. On the assumption that your 100€ was too low already (did you have to pay anything extra this year?), then you can reckon with 300€ more to pay on top next year, if you don't increase your monthly payment to 125€ as your landlord suggests.
Just to recap, Nebenkosten are not a part of your rent - your rent is the price for the flat "cold", i.e. without any services. Having said that, the charges for the Nebenkosten have increased so much in recent years, that even the Germans have taken to calling them a second rent!