Hi Kirsty,
From what I've read...Yes, its over heating and the pump will no doubt need replacing. There is a post about this on this site
Have you seen the advert with Jonny Ball on the TV? The one about a new boiler for a low amount under £??? monthly and this includes Repairs 24/7...Look out for the ad on the telly...call the number.
http://www.miketheboilerman.com/index.html this link I take No Responsibility for...However, he does list all the faults with known boilers and how much (roughly) to fix them, what's involved, etc. You might want to email him for a 'Chat' about cost. Make sure you check him out on the Gas Reg Site if you decide to take his advice...be on the safe side. Do you tick the box for help from the DHSS? They have means to help you contact you local Job Centre/or look in the phone directory for more info on Heating Grants/Assistance. Scroll Down on this link...there's a few contacts and lots of info that may help you.
http://www.energychoices.co.uk/heating-grants-ask-our-expert.html
The Same Question As You:here:http://www.howtomendit.com/answers.php?id=301858
fedup68
September 2011