Credit balance

Last week Friday I made an online purchase, I was then contacted and was informed that some of the items that I had ordered were out of stock and instead of making a refund to my debit card they were going to put credit onto my dischem profile which will be available immediately and I can use to pay anytime I wish to make a purchase and as promised they did. However now that I am trying to make another purchase I am unable to pay using the credit balance, I have gone to a dischem store to get assistance and they could not assist me, I have sent emails and I am not getting assistance, I have made calls still no assistance, I called the store directly that called me for further assistance and the gentleman said that they had issues with the website and the matter was resolved yesterday and I tried to make the purchase again and there is still no option for me to use the credit balance, I am quite upset because I have been trying to get this resolved since Saturday and I am just not winning and i am being inconvenienced in do many ways.