Amber Denyer, 25, says a manager in the Tesco Extra store in Batley, Bradford, would not assist her when she said two-year-old Layla was lost.
A security guard also allegedly refused to look on the CCTV monitoring screens for the toddler on the basis he was 'not allowed to'.
Frantic mum-of-three Amber says she was left to search the aisles of the store herself for twenty minutes. She eventually phoned her father and asked him to come to the supermarket and help her - fortunately she found tearful Layla by the store's checkouts just before he arrived.
"By this time I had lost all hope," Amber told her local newspaper. "I was literally running up and down the aisles. I didn't know whether to ring the police, I didn't know what to do."
The relieved mum said her little girl was very upset and begged her not to tell Father Christmas that she had wandered off!
"All she said was 'don't tell Santa'. I think she thought she was going to get into trouble," said Amber, adding that Layla had become 'clingy' since the incident and 'was not herself'.
The angry mum has now filed a complaint with Tesco. The store's head office issued an apology over the incident, but Amber says she is still waiting for the Batley store manager to call her and explain what went wrong.
"I'm not trying to get a free shop," she insisted. "I just don't think they understand how upset I was. I just want an explanation."
A spokeswoman for Tesco said the company had 'strict procedures' in place for missing children, and they she was 'very sorry that they weren't followed on this occasion'.
"We will be taking immediate steps to remind our staff in the store of their responsibilities," she added.
Poor Amber! Have you ever had that heart-stopping moment when you realise your child has wandered off in a busy supermarket or shopping centre?