Plant labels are not all they appear to be. Sometimes, it doesn't matter. Looking at these two Clematis in the images below they look very much the same and both were labelled as Clematis montana " elizabeth". The plant in image bottom right was bought when not in flower. There is a difference between the two plants, although not one you could see, the Clematis in image bottom left is beautifully scented with lovely soft vanilla scent which is why I selected it for the planting scheme. I created an area in the garden with a scented archway planting lavender, roses, honeysuckle and Clematis montana"elizabeth" to give scent from May, (starting with the Clematis,) to October, and so it mattered that the Clematis was exactly the right one. The same thing would apply if buying plants to create a white garden, you don't want to find out that one variety is slightly blue.
I am now going to have to dig up the rogue plant, and re plant another for next year which is not ideal, especially as I didn't keep the receipt so I cannot remonstrate with anyone but myself. This time I think I will give the garden centre a miss and go to a specialist Clematis grower on the internet and get an assurance it is the correct variety. Planting it twice is one thing, but I am definitely not planting again. I will try Thorneycroft or Taylors, and hopefully this time I will get the plant I expected. Clematis are a really popular garden plant and not as difficult to grow as their pruning requirements can suggest; more about Growing Clematis . Best tip: if buying Wisteria definitely buy one which is in flower. Wisteria can be tricky to get into flower, if you buy one that is in flower at least you know as a good starting point that it can flower, after that it is all about pruning. The Wisteria left is flowering well and I have carefully pruned it twice a year; tips and advise on growing Wisteria