Barclays is setting aside £1bn to cover the cost of mis-selling of Payment Protection Insurance (PPI), the bank has announced.It said it will not participate in any application to appeal against a High Court Judgement dismissing a bid by the British Bankers' Association to overturn a ruling that banks need to pay compensation to customers who were sold PPI without knowing they were buying it.Barclays also said it would begin to process all complaints from customers about their PPI policies and will contact them and assess their complaints as soon as possible."We have taken this decision because it is in the best interests of our customers, as well as for Barclays and its shareholders; creating certainty, particularly regarding past issues, is of benefit to all parties," said Barclays chief executive Bob Diamond."We don't always get things right for our customers; when we get them wrong, we apologise and put them right."Last week, Barclays' rival Lloyds made a £3.2bn Payment Protection Insurance (PPI) provision.PPI is meant to provide a safety blanket to ensure that in exceptional circumstances, such as illness or redundancy, loan repayments are maintained, but the policies have been widely criticised as being so full of small print get out clauses for the financial service provider as to be practically worthless.