Apismalifica, I'm sorry I'm really not qualified to advise you, I can only sympathize and share experiences from when I was in the situation of taking over and chairing the meetings on behalf of a young family member who purchased leasehold with share of freehold (held by a limited company of which all property owners are equal shareholders) In this particular case of the five shareholders, some are very long term, others newer and one an absent landlord. The situation at the time was that feelings ran high with some feeling frustrated at lack of progress and others feeling bullied, as a result nothing ever got done despite, as you say, minuting all the right ideas.
After an awful lot of work I managed to get the majority on side as being of the same mind and approach.
There are obviously always issues and maintenance (such as the roof and fabric of the building) which are equally for the good of all, and then there are issues which are of self interest, where things can never be equal. Agreed, it's hard to persuade those living in the basement that the roof is a real priority, but if you buy an apartment you can't neglect communal responsibilities and I had to keep ramming that point home.
At meetings, for most items, majority rule carries the vote and if a shareholder is to be absent they were requested to submit their vote in advance, appoint a proxy or be recorded as having abstained.
It's this kind of thing that an independent agent can assist with and we're fortunate that ours offers a service which is excellent value for money.
I and another shareholder have had to be extremely strong and insist upon raising the monthly charge, making sure it was collected and trying to establish a 'sinking fund' which was lacking at the time of purchase. I kept pointing out that a well run and adequately funded property was more of an asset than one falling into disrepair and not on a sound financial footing. We had really fallen for another property, however, rejected it as repairs were funded on an adhoc basis as need arose, with no provision in the accounts for contingencies - far too much of a risk.
Here's a link for some background reading which will help clue you in a bit more as to the rights and responsibilities. Read the bit about serving notice, although if the payments requested are up to date, I'm not too sure where you go from there. See also Here
Is your monthly service charge adequate for the building's needs? is it on a par with other similar properties in the area? I lobbied for a £30 pcm increase which had been very long overdue and brought the amount more into line with other similar properties. I also suggested and was successful in raising a one off end of year contribution to boost the bank account a little.
It really does sound as though you need a crisis meeting to make people fully aware of how urgent and crucial some expenditure is and a third party can definitely assist with this, as I say, taking personality and personal interest out of the equation and dealing with cold, hard fact.
If I were you I'd post a short message in Legal asking how to proceed if shareholders won't acquiesce to spending on vital repairs.
Good Luck.