Water only hot for a couple of mins then runs cold!! HELP

HELP!!

We have had this problem since November and everyone seems to just pass the buck so your help would be very much appreciated.
We have a pulsacoil boiler in our flat on an economy 7 tariff, the water is only running hot for a couple of minutes and then goes cold. We have had the elements in the boiler changed and both now have 11" elements in top and bottom. The plumber said that we now needed an electrician as everything he could do was fine.

We then got an electrician who said:
The electrics are working fine there's power going to the tank and the time clock is working fine as well. I didn't change any parts. The only thing wrong was the element inside the tank that heats the water. It must of been faulty and that was causing the breaker to switch off. The plumber changed the element and what I think the problem is is that the element which he's put in is not heating the water enough. I think this is because the time clock thats already there is an economy time clock and you can only have it on for 5 or 6 hours at a time. With the old element 5 hours would of been enough to heat the tank, but with the one he's put in it needs more than 5 hours and I cant adjust the time clock to heat for longer because of it being an economy time clock.
This is my opinion and I really cant see it being anything else. They are getting some hot water so the water must be being heated, but just not enough.
The two things you can do is change the element again or I can put on a new time clock that can be adjusted so it has power going to the tank for longer than 5 hours and therefore heating more water.

We then called our electricity supplier to ask to change the heating time to 7 hours, they sent out an engineer who replaced the main meter downstairs and then suggested that it must be the elements (although these were new) and to call a plumber!
We are now back to square one and really stuck with what to do next! we have hardly no hot water and are really sick of the whole situation now. We have briefly spoken to gledhill who said the can send an engineer out to look but we'd have to pay the set fee of over £300!! therefore we declined.

Once again your urgent reponse would be really appreciated and i am sorry to go on abit but wanted to make sure you had all the info to diagnose this problem. We are in Blackpool or i would have had you out to sort it!

Kind Regards
Gemma

by the way: the storage heaters all work fine, its just water which is affected.

Pulsacoil?
A class?
2000?
Mike
MGC/H2O
Norfolk

yes its a pulsacoil although not sure which model.
Thanks

Hi Gemma,

Is the Pulsacoil getting hot in the cupboard?

Regards

Gary