climbing plant

I have a climbing plant with varigated leave that flowers in May with a vivid blue cone like clusters of flowers. Can not remember the name. It is in place over the archway my DH installed several years ago. This plant suddenly seems to have had an attack of 'jack in the beanstalk' and it is now top heavy. In fact in the strong wind yesterday a large branch at the side snapped off. Is it best to cut the whole thing down to the top of the arch , will it grow again? It was my husband's pride and joy and all the neighbours commented on the flowers when in bloom so i dont want to ruin it by having it pruned too hard. A neighbour has offered to do it, or should i go with a proper gardener? What would you do?