How to stop a pipe rotating in 3d print

[vampiro2004]

I have a holder for kitchen roll that i have designed that stands vertically on a pipe with two seperate snap lock pieces to fit round the pipe. Its desgined to save space. The problem is that it is slipping around the pipe as it is circular and so is my design. My question is what shape can i use to stop it from doing this?

I have attached the f3d file for my project

[TheCADWhisperer]

@vampiro2004 

I don't know what happened - but notice that there is no longer a red lock symbol on your Sketch1

Click and drag point from the Origin...

There is an unconstrained endpoint on a Construction line.

Make this white dot Coincident to the Origin.

[vampiro2004]

@TheCADWhisperer 

Thanks for the video. can you check everything look okay on the attached file