Slow refund process

I switched to another insurer as of 24 March 2024 and notified them of this ahead of time so that they don't debit my account but my account was still debited on the 25th of March. I asked them the same day to refund the debit as now I've paid for 2 insurance covers and defeats the purpose and was told that I'll be refunded once the money is cleared with my bank, the next excuse was that my refund was only captured on the 27th etc etc.

In the meantime my other debits are bouncing as a result of this and causing unnecessary fees.

Just pay me back my money, It shouldn't be difficult.