Ollie,
I would test again and go carefully using a low moisture approach at first.
Look for evidence of colour run , has the customer cleaned off spills in the past with detergents, did this cause a problem.
Reds will often give a colour transfer but will not actually run.
Remember if you do not use much water then colour run is much less likely.
Also use a neutralish cleaner , like a woolsafe product at least until you are confident colour run is not going to be problem.
I've cleaned 5,000 suites and only. had colour run problems on a handful
Cheers
Doug