Not getting a refund for cancelled contract and getting billed further.

My mum was going to join ID, but she decided just hours after placing the order that she didn't want to go ahead with it. Despite contacting customer service and the phone not yet being dispatched to DPD, they told her to refuse it upon the delivery attempt. She did exactly that. Over a week later and they only managed to return it a few days ago back to Curry's. She has not been refunded (which I understand can take up to 2 weeks (if they even bother)) but she has also received a bill, despite making it clear on several discussions with customer services that she wanted to cancel the order and contract from the very first contact with them. The lack of response or care from customer services is honestly almost laughable. Especially the lack of knowledge from the agent who felt more like making sense of a conversation when talking to someone on Reddit. I'm at the point where this is getting quite frustrating, and all of this is happening whilst I am renovating my little brothers house for him. Being my mum's carer on top of all this as well as other problems we are currently facing, I wish I never knew ID mobile, because the customer service has been as useful as a rock to float in a river.