Addressing his first annual meeting in Edinburgh, Mr McEwan hinted at a culture change and highlighted the bank's raft of initiatives to regain customer trust.
But RBS chairman Sir Philip Hampton told the meeting further branch closures were inevitable.
Noting RBS had "more branches than Asda and Sainsbury stores combined", he said: "With continued rapid change in the way people choose to bank there will inevitably be further branch closures."
Mr McEwan said RBS was no longer offering deals and products to new customers that it was not prepared to offer existing customers, it had scrapped "teaser" rates and zero per cent balance transfers on credit cards, and by the year end would have slashed its product range by 50 per cent.
"We are ensuring that pricing across the bank is consistent for personal customers and also ensuring this is the same for small business customers by the end of the year," Mr McEwan said.
He said dissatisfied customers would "make their feelings known via Twitter, Facebook, their relationship manager, their bank manager, or indeed myself ... so I want our customers, many of whom are also shareholders, to know we will prioritise our complaints handling".
Winning back customer trust would enable the bank to "reward the loyalty and patience of its shareholders". Mr McEwan said: "Change will not happen overnight, it will require hard graft, it will also require us to do things differently."
Sir Philip said that in 2009 he had set out "a five-year plan for how the bank would be returned to being a normal profitable business".
Last year's loss of £8.2 billion had been largely due to "customer re- dress, fines or other litigation costs whether from PPI, swaps, Libor, US mortgages and so on", the chairman said, adding: "The issues that have arisen were simply not foreseen."
Sir Philip was asked by shareholder Lynn McMillan why "obscenely large bonuses are still being paid to bankers", and why EU regulations appeared to be "toothless".
Sir Philip said pay structure in banks had contributed to the financial crisis as bankers had pursued short-term goals for personal gain and RBS "had its full share of that". He said RBS had done more than any other bank to address the issue, with bonuses down 60 per cent in the bank as a whole and 75 per cent in the investment bank. Top talent had to be paid competitively, but Mr McEwan had already waived a bonus, Sir Philip said.
Unlike previous annual meetings since the crisis the board faced no attacks from disgruntled business customers, with the exception of Gavin Palmer who likened the bank's Global Restructuring Group to a "mugger" of SMEs.
On Sir Philip's insistence that the bank had been cleared by law firm Clifford Chance of any systemic wrongdoing in the GRG, Mr Palmer shouted that the report had examined only recent GRG cases and was "full of holes".
Joel Benjamin, speaking for 'Move Your Money', said RBS had sold derivative-linked loans, at "obscenely high rates of interest" to local authorities and housing associations.
One authority Newham had refused to divulge details of its contract after a Freedom of Information request, claiming that the bank had wanted it withheld, Mr Benjamin said, asking: "Did the bank request that FoI be denied?"
Sir Philip said: "I have no knowledge of anybody doing that."