Rescaling tommee tippee perfect prep

The calc light was flashing so descaled the machine for he first time following all the instructions - there was differing advice on using vinegar or sterilising solution so used Milton as that's what I had. Did all the steps but the light is still flashing - any ideas?

Also my husband keeps telling me we don't need to rescale the prep machine or the electric steriliser as we live in the UK but I still feel it's best to do it anyway - does everyone else descale?