Can I ask , what you are paying for? I am paying for the (up to) 25 mbs but i rarely ever get 5 - 6 mbs...and i have tested it at all hours of the day over a very large period.
I am getting 20Mbs at the moment and will be upgrading to 40Mbs soon.
90% of the time I achieve 19-20Mbs, but we are in a very fortunate place as the main internet line for the region comes into my town, so we get first pick so-to-speak.
The marketing ploy of using 'up to' has been criticized by Ofcom in the UK as misleading as in reality users very rarely achieve the speed that they are told they 'can' get and it seems this has been mirrored in Poland.
Are internet connections in Poland mainly Cable or Telephone exchange?!
It varies, as in my town we have fibre optics, but this is not common practice at all. Most rural communities are run through the Telecom system with many still using aluminium cables which are terrible for loosing data.
Most cities will have cable though.