Hindsight is marvellous! You have to remember that back in 2005 it was not realised how great a tracker mortgage was going to turn out to be, well unless you were one of the economists if even they knew.
Not all banks offered trackers on all loans, there were different promotions for various categories of borrowers like first time buyers or buy to lets or whatever. There is no reason to believe you were given bad advice, you were given advice suitable to the times we lived in. No one ever hears of the people who had the option of trackers and did not go for them and believe me there was plenty that did not, people are always suspicious of new products which the tracker was and many opted for standard rates. Obviously if we all had a crystal ball then things would be different.
Discounted for year or so mortgages were hard to refuse as most people need a bit extra in the first year so many chose the same option as yourself and I don't think brokers got any more for that type of mortgage, in fact if anything the type a broker would prefer would be longer term fixed as there was usually a claw back of commission if the loan was switched within a certain time frame.
So there is no point beating yourselves up about what you did or didn't do or whether the advice was bad or not, unfortunately this does not help you much now but you are far from alone in your present predicament.