Hi Heather. I've never heard of this plant. Do you mean Clematis...? If so, then we'll need to know which Clematis it is, as the different varieties require different pruning regimes. If you don't know the variety, then some photos will be needed, including close-ups of the leaves and flowers.

Yes, Rosie is right. We need a bit more info about the plant. What size are the flower, what colour, when does it flower and for how long. What size is the plant now?..That would help, if you can't get the actual name.

If the label said do not prune then I would expect it flowers before June. I was told a rule of thumb says flowers before June do not prune BUT the RHS advice on pruning says regular pruning of all clematis keeps them strong and prevents you ending up with very long stems which flower above head height. This link gives you their opinion.
https://www.rhs.org.uk/Advice/Profile?pID=109&cID=256