Jet - Lay-byes policy

Went to the shop on the said date to lay-bye a pair of shoes, I asked a guy who is an employee about the procedure and he told me that I can do it but not on sale items. Excitement got me and I took that pair which was also the last one on my size, went to the cashier to be assisted with my lay-bye.
To my surprise I was told that I cant do Lay-bye on one (1) item only, I explained to her that I will release them on Friday cause it was the only one left for my size and others are small sizes. I went on to ask if they can put them aside till Friday and the lady said no its against the shop's policy.