No refund after 3 months

I order a laptop in December 2019 and returned it end of December , Dell Canada received it early January.

Since then I haven’t received my refund for that order.

 I have been in touch with English support but they literally told me to deal with my bank to claim the charge back from my credit card. Very hilarious but not serious at all! 
Dell denied its obligation to refund returned order within 2-3 weeks as advertised .

 I then contacted the French support, someone took over my file and I was confident to get the refund but then the financial team as been completely un professional, they let my case slip and the refund went expired . I ve been fighting with them for 3 weeks now.

How is that difficult to issue a refund Dell? Any store is able to refund money on a credit card in minutes. Not you?