70% of the time this would be due to a faulty heating element, a replacement element can be sourced here for around £85.
It would be worthwhile having this fitted by a qualified person, if you provide me with your postcode I can recommend a suitable engineer in your area, who can attend verify the element is at fault and replace it for you.
Please let me know if I can be of any further assistance.
I havent heard back from you please let me know if you have any follow on questions.
So I can claim payment from JA for answering your question, I would appreciate if you can rate the service received using the star rating on the question page.