Ity seems like the Russians still have a long way to go to catch up with the number of failed launches of the Arianne programme during the 1970's, 1980's and 1990's.... The swamps of French Giuana are littered with pieces of Arianne rockets and payloads....
The ISS is accumulating damage even as you read this, from micro meteorites, space debris, solar radaition and cosmic radiation.... all serve to gradually damage its structure.
By 2024 it is predicted that the ISS will be uninhabitable and unservicable.
The ISS does not have chemical rocket motors capable of adjusting its orbit.... it has too much mass built onto it and its modular structure would not stand up to the forces generated by any rocket motors subsequently attached to propel it into a higher orbit.
The ISS's specific impulse plasma maneuvering thrusters are for attitude control but are unable to provide enough thrust to move it to a higher orbit. Although specific impulse plasma thrusters offer very high eventual speed than chemical rocket motors, they have the thrust of a human fart and have a very slow accelleration rate, which is why they were chosen as the ISS's maneuvering thrusters.... they are simple, gentle and very cheap.
Basically if they fired all the appropriate plasma thrusters now they would still not have enough velocity to move tot a higher orbit and save the ISS by 2024.
This is why it has been calculated and decided that the ISS will become a veryreal hazard to the Earth in 2024 and should be crashed in a controlled manner into the ocean without risk to human life.
After large parts of Sky Lab peppered Australia, after surviving re-entry, they are taking the ISS's fate seriously.
That is why it will be destroyed in a controlled crash in 2024.... it will make quite a spectacular fireworks display and a lot of it will survive to impact the ocean.