Laybuy

I opened a layby @Truworths Tygervalley. All went well or so I thought,payments was made with just the slip.Hence now that I want to make the final payment and collect I was told I need my id. Never was I told that I must bring my ID with on collection. I asked to speak to the manager and was dismissed with a unfortunately that's the policy. I went through the T&C's on my layby slip nowhere does it state that the ID is required. I also asked 2 sales assistants to show me on the slip where it state about proof of identity other than the Truworths slip I have. They could also not find it but agree I need proof. In all of knowledge of laybys your slip is the proof of purchase???