If you might have been mis-sold a Payment Protection Insurance (PPI) you can expect a letter from Card Protection Plan Ltd  (CPP) the company set up to deal with claims under the scheme approved by the High Court of England & Wales.
The Financial Conduct Authority (FCA) has produced a step by step Guide available here. Note Step 3 “Making a claim yourself”. Claim handler or claims management companies offer to do the claiming for you for a substantial percentage fee. But the FCA explains that “making a claim for mis-sold PPI is a free, straightforward process that you can do yourself”. Do read the FCA Guide and do check that anything you read anywhere is from Card Protection Plan and not another company with a similarly evocative name.