I need my refund from Deco Essential

I've bought some catering equipment at Deco essential and I found out that the caurier charge is too high, the I decided to cancel my order and request my refund. The Deco Essential promised me to refund me even today they haven't refunded my money. When I called them they keep saying they they will talk to the finince department, and they will get back to me and they don't contact me up until I contacted them and they always tells me one thing every time I contact them. They've requested my banking details and I gave them and told me that it wii take seven days to appear into my bank account, even today I haven't received any payment from Deco essential. Please I need your help.