If you find discrepancies in your phone or internet bill, it's possible to dispute the charges. This could be due to errors on your provider's part or exceeding your billing limit.

Initially, double-check the bill to ensure there isn't a valid reason for the increase, such as international usage or purchasing additional services. 

If you believe your provider has made an error, contact them to rectify the situation. Since October 1, 2018, phone contracts allow users to set a 'billing limit,' preventing charges beyond an agreed-upon amount.

If your provider exceeds this limit without permission, you are not obligated to pay the surplus. 

To dispute a bill, reach out to your provider and request a reduction to the agreed-upon limit.

Contact details will be on their website, including phone numbers, addresses, and email or webchat options.

You can always use a template letter from the Citizens Advice website if writing an email or letter. 

If communication occurs via webchat, save the conversation for your records. If your provider's response is unsatisfactory, follow their internal complaints procedure.

If issues persist, consider utilizing an Alternative Dispute Resolution (ADR) scheme, an independent entity that evaluates cases impartially. Identify the ADR scheme your provider is associated with on the Ofcom website. 

Be aware that a late payment charge may apply if your dispute is unsuccessful, and the bill remains unpaid. Consult your provider's terms and conditions or website for relevant information. 

If you receive a bill after cancellation or switching, ensure you followed the provider's cancellation process.

Request a refund, halt payments through your bank if necessary, and escalate the matter through the provider's complaints procedure or ADR scheme if required. 

In cases where you are the sole individual named on the bill, the service provider can pursue you for the entire amount, even if others shared the service.

If there is a joint contract you are collectively responsible for bill payments, regardless of individual usage. 

For lost or stolen phones, users are typically responsible for charges until the incident is reported. Refer to guidelines on dealing with lost or stolen phones. 

For additional assistance, contact the consumer helpline at 0808 223 1133.