The only outstanding issue is whether the friend's solicitor had done thier job properly. If they had been more on the ball would it have been possible to exchange contracts wit hthe builder ten months ago, or did they try to and the builder put the transaction off? If the former the solicitors may have some explaining to do and compensation to pay. From the way you report matters it does sound as if they may not have done a very good job. They ought to have made sure that the contracts were exchanged, and kept your friend advised of what was going on, including their inability to get the builder to exchange, if that is what happened.
Exchange of contracts usually takes place over the telephone using a Law Society formula, and the friend's solicitors should never have been in any doubt as to whether or not they had achieved an exchange.