Please Help Me I have some cold radiators

I have a 3 year old alpha CB28 combination boiler boiler which is in the loft, but the radiators are much older.

My problem is the 4 upstairs radiators are hot,downstairs the kitchen and hall radiators are hot, but the lounge, dining room and study radiators are luke warm, and the conservatory and utility which are the furthest from the boiler are cold.

could it be the pump

Yes it could, or there could be an accumulation of sludge slowing things down. First though look up "Balancing" (FAQ section) to see if you can get water going evenly everywhere.

I have turned upstairs rads off and am getting most of downstairs rads hot except the 2 furthest from the boiler.

Now turn downstairs ones off with the exception of the 2 cold ones.

Done that, and they come on, but when I turn other radiators downstairs back on these two go off again, also when I turn upstairs rads back on the downstairs stay on, but no where near as hot as upstairs.

I have tried balancing them by turning upstairs once to minus quite a bit more, and this has made it quite chilly upstairs, but the downstairs ones are a bit warmer.

I have also found that if I turn two off upstairs I can get more heat out of the ones downstairs.

I have also kept a check on the boiler and it is turning itself off after about one to two minutes, stays off for about four minutes, and just keeps doing this.

The indicator neons that flash every five seconds when dormant, and illuminate continuouslywhen boiler is alight, are doing the same, staying on for no more than one to two minutes, going off when boiler turns off, and staying off, and flashing every five seconds until boiler lights up again, then on continuously for the next one to two minutes.

This is also the case when the hot tap is turned on.

You may have gathered that I am a woman trying to think like a man, and finding it very hard, I do thank every one for trying to help me.