Useful next steps
If the bowl is backing up, stop flushing. Say whether other toilets or drains in the property are affected.
Record the make or model if it is visible without dismantling anything. Concealed cisterns may need access through an existing service panel.
For a rented property or shared building, contact the person responsible for authorising repairs and explain whether another toilet is available.
To identify the appropriate water or wastewater provider, use Water UK's postcode lookup. A town name alone is not a reliable way to choose a provider.