Refund of an Incorrectly processed debit order after cancellation

I had a good relationship with rain, unfortunately I had to cancel my subscription as I needed to relocate. I cancelled with them way before the next debit order date and even confirmed with the agent on a call a few days before the debit order date and he confirmed that indeed my subscription was cancelled.

I then handed over my router and SIM cards on 25 May 2025. But on the 24th the debit order went through. I asked the agent who was assisting me at Queenswood Rain offices to assist me with the refund. I was told it will take 7-10 working days to reflect but I am still waiting on working day 15. Please urgently assist me with a refund. I called on Tuesday and was told someone from billing will call me in the next day or two and today is Friday still nothing from Rain.