I have a vine that produces cluster of yellow bell shaped flowers. It is either an allamanda or tecoma, I am uncertain. The vines are propped up against the exterior fence.

Anyhow, I trimmed the terminal portions occasionally and now they have grown wildly sideways and have become rather unruly.

Any suggestions on:

1. pruning them correctly in order to facilitate a less sideways growth;

2. how much is considered severe pruning?

3. any ideas on how to wrestle these vines to bring some order in their growth and appearance.

I am exasperated. Please help.