non flowering summer jasmines, bill mackenzie clematis

berarde

I've had these two summer jasmines (white flowers) for a long time. The one by my front door has never flowered properly, just a few white flowers at best. It has been there 14ish years and faces north east. I prune it back late summer, ie after the time when it should have bloomed. I cut it hard back this autumn wondering if this might encourage it. It can be a nuisance as it can push stems under the porch felt 

The one at the back is 25ish years old and has very occasionally flowered well, but usually nothing. It is south west but is shady from fence and the apple tree. It is vigorous and I have to cut it back at the top to keep it from climbing in the tree branches, but I don't prune the lower part until late summer. 
I'm inclined to remove both of them as they need a lot of cutting/ pruning with nothing to show. Having seen a lovely yellow clematis which I think is Bill mackenzie i am wondering about replacing the back jasmine with the clematis, but maybe it also is too vigorous?

Can I get these jasmines to strut their stuff or are there other suggestions?

nutcutlet

Bill Mackenzie is also huge.

Fairygirl

I wouldn't have thought the one at the door is in a very suitable aspect or location.
Don't they need a warm , sunny spot to flower well?
The one at the back is possibly suffering from too much competition for nutrients to flower well.

Alchemist

We have a lambton park which is a very similar to Mckenzie and both grow pretty big. I wouldn’t get rid of it any cost as the flowers on it are numerous and lovely followed by silvery fluffy seed heads that still looks great. Pruning wise, you’d cut them to the ground every year. I find this type of pruning to be a lot less easier than others that require careful pruning.