@SLP -
Really?
Firstly it was not a zombie thread... the post in January is probably why this topic appeared in a Google search, and as I stated I did not notice the original posting date. This is Internet, and if content is available a search will find it.
As for defending the indefensible, as PirateSmile pointed out sometimes needs must and I took the job exactly for that reason. I soon found out that I didn't like the methods used and simply started during my own thing, then I started my business and help people to avoid much of the hassle... they can complete a form on my website, I'll call them to see how many quotes they want and at what times, I contact the companies to arrange the quotes and inform them to cut the BS and just give the best price. I also inform the potential customer of the sales techniques, and how to play the 'game' to their advantage, an example of which I posted in my previous posts (e.g. print out the GGF code of practice and state you'll buy if it was a certain price), plus I follow up to see how things went and advise people where to complain if there has been a problem, and if needed I inform the company that their agent/salesman has gone against the regulations that are in place.
So I am not defending the indefensible, there is actually nothing to defend. The majority of problems come because people allow themselves to be manipulated in their own home, e.g. not telling the agent they don't want a quote, not telling the salesman to leave when they want them to, not saying they want a better price etc... but even worse they do not make the relevant complaints... this is where it goes wrong... the companies have to abide to the codes of practice but sometimes individuals choose not to, if people don't make the complaints the company doesn't know what individuals are doing, if people do make the complaints the companies have to address them and can deal with what those individuals are doing.
So, in reality it is individuals that give the companies at bad name and this escalates because people accept it as a bad experience rather than making the necessary complaints. I stated earlier that I no longer use one of the major companies, this is because their director was the problem and that filtered down throughout the company.
Unfortunately, the home improvement industry does require companies to visit potential customers before a deal can go through (e.g to measure up so the windows are the correct size), this is unavoidable, but it is how best parties act that set the way things go... when you work on commission you need deals to go through to earn your money, this can make people quite forceful so potential customers need to be more forceful in return... if this happens there should be no problems.
So SLP, if anything is mildly amazing it is people's lack of defending themselves against the known sales techniques of these companies. If you allow any home improvement company into your home remember it should be on your terms, not thiers.
Of course, this thread was originally about Zenith and I've seen stuff posted like 'don't let them in to your home' or 'they were a nightmare'. One thing for sure... those who went into the home and made it a nightmare were going against Zenith's guidelines and Zenith should have been informed so it couldn't happen again to someone else. That doesn't happen and you end up with post topics like this one... to answer the original poster's question... YES, you should have complained because I'm sure the problem would have been addressed and this post topic would never have been created.