[TYPO3-mvc] problem with cache

[Dawid Pacholczyk]

Hello List,
  I have a problem with cache in extbase. I have single view of my 
record where I have few variables. For example a button is shown only 
sometimes or available places on my course are changed every time by the 
system when someone registers on it. But cause of cache it`s always the 
same. Can I clear cache from extension level ?
Or can I set some parts of my fluid template as non cached ?

Best regards,
Dawid Pacholczyk