Bad customer service

I bought an office chair from Leroy Merlin's online website. Two days later I was informed via email that my order was declined as they had no stock available and that I would receive a refund which was not the full amount I paid. I rep****, requesting my full refund and advising against advertising out-of-stock items online. It has now been over two weeks and I have not received my refund. The level of service is extremely disappointing and I would not recommend buying anything from them.