Hello
I have had Roca Victoria (single flush) slim toilet for 10 years and it started to play up and have used the following solutions:
1, The filling system can be changed to a Torbeck bottom feed system, but it is a small feed size so check with plumbers merchants first. Adaptors available
2, The toilet constantly running and refilling a about every 5 to 10 mins.
There are many posts about changing the small light grey washer on the bottom but make sure you clean both side throughly as lime sacle builds up between the seal and the polystyrine float.
When refitting make sure the cistern is vertical because this can prevent the float to seal correctly.
If this doesn't work or the unit breaks its £34 plus del plus vat. Don't worry Torbeck make a replacement called a Variflush drop valve ( less than £15 at focus or DIY). it is fitted in minutes and has the added benefits of being a dual flush system with complete new chrome twin flush button assembly.
I believe this will work on twin flush Roca systems.
3, The broken chrome button these break easy and are £18 plus del plus vat. What a rip off! just buy the new Torbeck system above and it sorts both known issues.
This is a great site thanks to the other people who have been posting answers.
Please note Screw Fix also have a new type from fluid Master which is £10.99, but I have not tried this out.
I hope this helps.
Ian Pearson, October 2009