Similar thing happened to us, again with Bensons, but certainly not quite as bad as your experience Exdancer. We ordered a replacement double bed, had friends coming to stay, Bensons cancelled the delivery date which meant our guest room was minus a bed when friends were due to arrive so had to cancel that On complaining got some cock and bull story about a mix up at the warehouse, but found out subsequently the guy in the shop who took our order, hadn't actually placed that with the warehouse. Then when the bed actually arrived it didn't have the headboard which had been ordered as an addition but was supposed to be delivered at the same time. I asked their customer relations department to give me the name and number of the CEO, they didn't do that but one of their trouble shooters offered me either a £100 gift voucher or a £60 refund I took the latter as my experience told me I wouldn't be ordering anything else from them.
Yes I would definitely ask for a full refund they have let you down badly.