Taking double money that needed to be refunded

My husband went to buy a products and when he got home it wasnt the correct product. he immediately returned the product to builders where they said they will refund him. instead of returning the money the deducted it once again so now he paid double for a product that was returned. they advised 7 days for the refund to be allocated back into his account, its now 30days later and when my husband goes there they tell him not be upset and that they will refund the double charge in 7 days. the *********** people working there does not realize its been 30days already and still no money. this is the worst service ever, and then they keep making promises but just takes more of your money instead of refunding you. we will fight this battle till we receive our money back and will never do business with Builders Warehouse ever again. i rather go to opposition stores.