Arbiter ignored cheating, and I signed the scoresheet. Did I lose my right to object? I am currently playing in an ELO tournament. 

Today, while I was playing, my opponent occasionally got up and walked around. At first, I did not care much. Then, I realized that some people were behind me, examining the game very carefully. 

At the moment there was a critical position, my opponent was not at the board, and three or four guys came around, and began to speak among themselves. I looked for an arbiter but there was only one and he was sitting at the other end of the tournament room. 

I made my move, and went to the arbiter. This is when the weird things happen. I told the arbiter that my opponent is never at the board, and there are some people coming when he's away. There are cameras everywhere, so he is free to check.

When I and arbiter were walking back, there were three people around the board, talking to each other and pointing at the game, and my opponent was also at the board, listening to them. 

I immediately said that I demand a rematch at the least, since this is not the first time. Arbiter spoke to my opponent and his response was "he said that they were speaking about something else, I warned him, and this will not repeat again."

He also told me that if I don't sign the scoresheet, it counts as I did not play the game, and I cannot claim anything. So, I completed the game, signed the sheet, and told the arbiter that I will write this to FIDE.

I have written a mail describing this situation. But I'm not sure if something will change. In case such situation happens again, how should I proceed?
According to the 2017 version of the Laws of Chess, rule 11.10 says:


  Unless the regulations of an event specify otherwise, a player may
  appeal against any decision of the arbiter, even if the player has
  signed the scoresheet (see Article 8.7).