The cooling-off period starts the day after you agree to go ahead with the service.
Cite the relevant legislation in all your correspondence with the trader when explaining you wish to cancel your contract.
If you want to cancel your contract, such as a mobile phone contract, you must write to your supplier within the cooling-off period to tell them you want to cancel.
If you're close to the end of your cooling-off period, you'd be better sending an email. If you were given a cancellation form when you signed your contract, you can use that.
Otherwise, you must clearly outline your intention to cancel your agreement in the letter or email that you write.
Keep a copy of all letters and emails you send to the supplier of your contract.
As long as you send your cancellation notice to your service provider before the end of the cooling-off period, it doesn't matter when it's received.
If you're sending a letter in the post, be sure to send it recorded delivery. If you send an email, make sure you keep a copy of the email.
You don't need a reason to cancel your contract. If you've paid a deposit ask for it to be returned.
If the company refuses to let you cancel or refuses to refund your deposit, write again stating that you're legally entitled to cancel within the cooling-off period and get at least some of your money back.
Warn the supplier that if it continues to refuse to send your refund, you'll have to consider taking court action.
Tell the supplier that you'll also report it to your local Trading Standards department.