A cancellation request is only useful if the company received it in the way the contract requires. Many people send a letter, make a phone call, or submit a web form, then keep paying because nothing came back. The gap between what was sent and what was received is where the trouble starts, and it is far easier to close before the next payment than after it.
Start with the cancellation clause itself. Read which method it names: written notice, a specific form, a mailing address, an email address, or a phone line. Then read whether the contract says cancellation takes effect when the company receives the notice or when you send it. Those are different events, and the difference can decide which payments are still yours to make. If the clause is silent on method, note that in your own records and ask the company in writing which route it accepts.
Keep proof of what you sent. For a letter, keep a copy of the signed notice and a receipt that shows the mailing date and the address used. For an email, keep the sent message with its header information. For a web form or an account portal, take a screenshot of the confirmation page and save any reference number it shows. For a phone call, write down the date, the time, the name or badge number of the person you spoke to, any call reference, and what you were told, in plain words. A phone call with no record is hard to prove later, even if the person on the line agreed to it.
Ask for a written acknowledgment. A short reply that names the contract, states that you requested cancellation, and gives an effective date is the document that settles the question. If none arrives within the time the contract or your state's rules allow, send a copy by the same method with a note asking the company to confirm receipt. Do not rely on an automated reply alone unless it contains the contract reference and the effective date.
Check the next statement or the payment record before you assume the request worked. If a charge posts after the effective date, write down the amount, the posting date, and the contract reference, then send that with your copy of the notice. Ask which refund method the contract uses and how it calculates any refund, since the contract's own terms govern the figure, not an estimate from anyone else. This explainer does not describe any company's cancellation terms and does not promise that a refund will be paid.
Some states set cancellation and refund rules in their service contract statutes. The state pages on this site name the statute or program that applies and print that state's roster where one is published. Check your state's page before you send anything, then compare its cancellation rule with the clause in your own paper. Where the state page and the contract differ, record both and ask the company which one it is applying. Each state page also says what this edition has and has not read, so check that line before relying on the page for a particular question.