Well, since we are in November, do you think it's just going dormant for the season. How would anybody look if sleep deprived? No fertilizer now, wait until it wakes up in the Spring. You can give it a trim now, to get rid of the jumbled branches - just keep 2 or 3 of the strongest leaders, trim off the gnarly bits.

Don't water it any more until it resumes growth, you might encourage rotting roots.
You could thin the branches & lightly tie in the stems with good air circulation in mind. Then use the trimmed parts to make semi-ripe cuttings, the RHS website will have 'how-to' details for trachelosporum

Have a look at Brentsa's latest blog re fertilizers! Sending encouragement to your jasmine!

As Bathgate says, don't fertilize at this time of year, its going into dormancy. Trachelospermum jasminoides likes full sun, or as much as it can get (minimum half a day) and they are slow growers initially, they can take up to 3 years to really get going, though more usually two years. Leave it alone for now,, check it in spring and if its still hanging on, fertilize then (where you are, probably in April rather than March, unless the spring is very mild and growth has begun generally in the garden) using a general purpose product such as Growmore.. And don't prune it either, if it really hasn't got many stems nor put on much growth, just leave it be till next spring. You'll probably find some tip burn in spring if we have some very cold spells in winter - just trim back in spring.

Can be quite temperamental. As said, sunny, protected situation. No pruning and no fertiliser until it starts to put on new growth in the spring. Not willing to put the mockers on it so to speak but most good garden centres have a 3 to 5 year 'Garden Centre Association' guarantee and if you still have the receipt or the original plant label perhaps be prepared to take it back in the spring. After all these plants aren't cheap!

Thanks all! Have read and understood!
Funny how a bit of sensible feedback can be so reassuring. Will stop worrying.... until spring! Thankyou.
PS my other star jasmine is thriving so fingers crossed.

If you live in a cold climate, you may have better success with Winter Jasmine (Jasminum nudiflorum). You seem to be right on the threshold of what Star Jasmine can handle but you should expect some winter die back.