Refund for the deposit amount

I returned a rented vehicle on the 12/02/2018 and I was promised that it would take 24 to 48 hours for the refund to be processed. It is now 4 days later and I have not yet received my refund. It is not the 1st time that I have experienced this kind of service from this company. I'm seriously considering taking my business elsewhere, this is an utterly poor service and I am not happy about this. If my money is not refunded into my bank account by today, I will take this matter further!!!