Boiler - repair (free) or replace (expensive)?

My boiler (a Worcester 24i) has been playing up ever since we moved into our current house about a year ago.

By playing up I mean that every few months it stop working and we have to get it repaired. The usual cycle is one morning you turn on the shower and find that the water is not getting hot, you think ‘!!!!!! the boiler is playing up again’, turn off the shower, go out to the boiler, turn it off at the mains, wait a few seconds, turn it back on, turn the shower back on and the boiler ignites and the water starts to get hot. Sometimes that is the end of it, bit more often than not the next day you have to repeat the cycle twice, then the next day three times, etc until it gets to a point where the boiler will just not ignite however many times you turn it / the hot water tap on/off. We then call the ‘boiler repair man’ out.

The problem is that I have never had the impression that the engineers who attend actually know what they are doing. Effectively they just turn up and say that a part (which I think they choose at random) is broken and they will order a new one. Another engineer then turns up and comments that there is patently nothing wrong with the current part, before saying they will put the part in any way so they can go to their next job. The boiler us usually fine for a few weeks to months before it starts playing up again. We had the circuit board replaced first. Then the clock/timer. Most recently the burner/the burner ignition [I think as 2nd hand info from OH who was there].

Over last few days my OH has been moaning that the cycle has started again. (Though it has been fine for me) and says lets just get it replaced.

The primary reason I have not had it replaced and I am reluctant to do so is that it is costing me nothing to have it repaired whereas as far as I can see a straight swap is going to cost me around £1350 (Is this price about right?)

The reason it is costing me nothing to have it repaired is that I have home emergency cover on my home insurance and everything it stops working I simply call up and say I am without heat and hot water and they send their contracted firm out to fix it.

A secondary reason not to get it replaced now is that we are considering having an extension built in a few years time and I had thought that this would be a good time to move the boiler (and possible replace the whole microbore central heating system.)

As an aside, not sure if it is relevant, is my boiler (reminder: Worcester 24i) too small for the house which is a 3 reception, 4 bed mid-Victoria terrace, over 3 stories, 1 bathroom (possible en-suite to follow), single glazed, solid walls.

What do people think I should do?

Thanks in advance for all info and suggestions

boiler not too small for heating, as hot water it can only do one tap at a time.

May be simple matter of sludge and or max burner pressure set too high.

need a competent engineer to diagnose and fix properly. better to forget existing firm even though they are free, get Worcester or ask in local parts place who is really good at fixing boilers. Better to pay properly for a proper fix (can always send bill to insurance firm and threaten solicitor with a diary of the repeated visits from their numpties). than to buy a new boiler. Your new boiler will end up the same in no time at all if you don't deal with two major issues. 1. the environment, (system water, type of shower, other taps in house, behaviour of OH<how long is she in shower for?>)2. who you allow to work on it.

I disagree Paul.

The OP has paid for insurance, so let the numpties throw parts at it.

Remember these cowboys are the same ones that undercut prices and de-value the trade, perhaps one day the insurance companies will cotton on, that cheap is not good.

As Paul said, the boiler is sufficient.

The problem you have is threefold.
The 24i is the smallest, cheapest model that WB sold at the time, and decidedly less good than the more expensive model.

As WB have a pretty good name, lots of cowboys quoted for these, hoping that the unsuspecting customer was made to believe they got a quality installation. Invariably the workmanship was as budget as the boiler, with lots of corners cut.

By the sound of it, your judgment of the repair guys is pretty accurate, and they didn't have a clue what they were doing.
Just keep getting them back; law of averages says that eventually they will either correct the problem by chance, or you might get a real engineer one day who finds the real problem and solves it.
Call them in the moment the problems starts again, as you said, it doesn't cost you.

A new boiler that will be sufficient for the planned ensuite, and of decent quality will cost a lot more than £1350, probably about twice that.
Best to wait until the rest of the work is done, and use the time to figure out exactly what boiler setup is the best for you, which will also give you more time to set aside the extra money needed for the better boiler.