I would love to know the Nyquil equivalent here too. Nothing I've found here so far is anywhere near as effective for relieving cold symptoms. Please let me know if you find a generic equivalent here.
For me I've found that my allergies make me much more susceptible to catching colds. To prevent allergies, I always used Flonase in the US. Here Flonase is available, but I use a much cheaper alternative: Lidil Cort Fluctisona. It doesn't actually work quite as well as Flonase, but I increase the dosage a bit to compensate. It's a topical nasal steroid spray, so of course the effect is not immediate. It's taken daily to prevent allergies and it begins to work after a week or so. In my experience it lessens the number of colds I catch, and also the duration of being sick.