Unacceptable explanations on delivery not happening

I made an online purchase on the 10th of November and selected click and collect express delivery. Delivery as per their tracker was the 14th of November. The delivery did not happen with the only information on the tracker as "we were unable to successfully complete the delivery of your parcel". When I phoned on the 17th of November I was told to wait a few more days and then phone back. Express click and collect should be between 3 and 5 business days. Can I please get a better explanation or time frame? I'm afraid these vague answers and being told to wait is definitely inspiring confidence with me that my delivery is going to happen.