How many more times are you going to ask about this?
http://www.theanswerbank.co.uk/Law/Civil/Quest ion660157.html
I suggest you pay a solicitor, or sit in the queue at Citizens' Advice Bureau if you don't want to pay for legal advice.
The answers you have received are valid.
As I understand it, you accepted the quote before the work was done, you just didn't realise that the quote excluded VAT.
If you have the quote in writing and it says �250 (ish) excluding VAT you may have a case.