Clematis flower

About this time last year or a little later we purchased2 clematis for our garden back wall and trellis.Over the last 2 weeks or one flower began at last to appear very slowly on one of the flower plants but didnt flower fully and then slowly died. Over the last few days the leaves of the flower now up to trellis on the wall started to go brown yellow black kind of and now it looks dead, though the stem appears to have life still.What could be the cause of this as we got plenty rain etc.The clematis flower is sown at the bottomn of the walland slightly shaded by a fuscia plant which has also always struggled with its leaves yellowish but never dies.There is another fuscia fhedging plant closeby on the same wall and this is doing very well with green leaves and growing mad.Curiously another clematis flower on the same wallis also slowly starting to flower fully and looks in good health.Why would you think the first clematis flower has failed and can it be rescued as doesnt seem fully dead on the stem we hope?Also any suggestions why one fuscia plant is doing better than another at the back wall?