I lifted my money from the ISA last month and I was penalised. However, I do think it was about £50 - but then again it probably wasn't a big amount maybe like yours.
If you read the terms and conditions Mandi you will find that you can't. If you chose the Isa because it had a better rate this will be one of the drawbacks
Conditions for ISAs will vary from one provider to another and even one provider may have more than one issue, each with differing terms. You need either to read the terms for your particular account or contact the ISA provider.